Patent Publication Number: US-11038822-B2

Title: Presence and geographic location notification based on a delegation model

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 15/011,082, filed Jan. 29, 2016, which is a continuation of U.S. patent application Ser. No. 13/015,818, filed Jan. 28, 2011, now issued as U.S. Pat. No. 9,281,961, which is a continuation of U.S. patent application Ser. No. 11/531,101, filed Sep. 12, 2006, now issued as U.S. Pat. No. 7,886,232, which is a continuation of U.S. patent application Ser. No. 10/849,565, filed May 20, 2004, now issued as U.S. Pat. No. 7,124,370, which claims the benefit of and priority to U.S. Provisional Application No. 60/471,743, filed May 20, 2003. This application is related to U.S. application Ser. No. 10/849,538, now abandoned, U.S. application Ser. No. 10/849,528, now issued as U.S. Pat. No. 7,219,303, and U.S. application Ser. No. 10/849,556, now issued as U.S. Pat. No. 7,237,201, all of which were filed May 20, 2004. Each of the aforementioned patent(s) and application(s) is hereby incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     This description relates to controlling distribution of notifications of presence and geographic location of users of systems such as instant messaging and cellular telephone systems. 
     BACKGROUND 
     On-line services may provide users with the ability to send and receive instant messages. Instant messages are private on-line conversations between two or more people who have access to an instant messaging service, who have installed communications software necessary to access and use the instant messaging service, and who generally have access to information reflecting the on-line status of other users. 
     SUMMARY 
     In one general aspect, delegation information associated with a communications identity may be used to manage the modification of notification setting information to control dissemination of notification information relating to the communications identity. Delegation information associated with a communications identity is accessed. The delegation information includes multiple categories of communications identities. For at least one of the multiple categories, notification information modifications to be controlled are identified. When an attempt to modify notification information regarding the notification setting information is received from a communications identity associated with a category of the multiple categories, delegation information associated with the category is accessed, and the communications identity is permitted to perform the modification (or prevented from doing so) based on the delegation information associated with the category. 
     Implementations may include one or more of the following features. For example, at least two categories of the multiple categories may be arranged in a hierarchical relationship such that a lower category is related to a higher category. Delegation information associated with the higher category also may be associated with the lower category, and the communications identity may be associated with the lower category. The modification to the notification setting information is only permitted when the communications identity is permitted to perform the modification based on a determination as to whether the communications identity is permitted to perform the modification based on the delegation information associated with the higher category. 
     The multiple categories may include a government category, an equipment owner category, and a user category. The equipment owner category may include a business enterprise and the user category may include an employee. The equipment owner category may include a parent and the user category may include a child of the parent. 
     In certain implementations, only a user associated with a government category is permitted to perform a modification that is associated with modifying the notification setting information related to notifying a governmental entity that provides emergency services of the geographic location of the user. A user associated with an equipment owner category is permitted to perform a modification other than a modification that is associated with modifying the notification setting information related to notifying a governmental entity providing emergency services of the geographic location of the user. A user associated with a user category is only permitted to perform a modification that is permitted by the equipment owner category. 
     Controlling dissemination of notification information may include restricting or permitting notification of the availability of the communications identity to communicate, or the geographic location of the communications identity. 
     Implementations of the techniques discussed above may include a method or process, a system or apparatus, or computer software on a computer-accessible medium. 
     The details of one or more of the implementations are set forth in the accompanying drawings and description below. Other features will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of a communications system capable of controlling dissemination of notification information related to an on-line presence and a geographic location associated with a user. 
         FIGS. 2A and 2B  are block diagrams illustrating aspects of the communications system of  FIG. 1 . 
         FIG. 3  is a diagram of a user interface for sending and receiving instant messages using an instant messaging service capable of controlling dissemination of notification information. 
         FIGS. 4A-4D  are diagrams of user interfaces for participant lists that indicate the dissemination of notification information in an instant messaging system 
         FIGS. 5, 6A and 6B  are diagrams depicting user interfaces for identifying temporal periods during which notifications of geographic location and on-line presence are to be permitted or restricted. 
         FIG. 7  is a flow chart of a process for indicating how notification information of geographic location or on-line presence is to be disseminated. 
         FIG. 8  is a block diagram depicting a delegation model that controls how notification setting information may be specified or modified. 
         FIG. 9  is a flow chart of a process for modifying notification setting information based on a delegation model. 
         FIG. 10  is a flow chart of a process for controlling dissemination of notification information corresponding to a communications identity. 
         FIGS. 11A and 11B  are diagrams illustrating an exemplary process for transmitting a notification of a geographic location of a user to a communications identity. 
         FIG. 12  is a diagram showing an exemplary process for transmitting a notification of on-line presence of a user to a communications identity. 
         FIG. 13  is a flow chart of a process for enabling a user to override applicable notification settings. 
         FIGS. 14A and 14B  are illustrations of relationships between linked accounts. 
         FIG. 15  is a flow chart of a process for sending notifications of on-line presence and geographic location for multiple linked accounts. 
     
    
    
     DETAILED DESCRIPTION 
     A user of an instant messaging system may store names of other users of the instant messaging system on a participant list (which may be referred to as a “buddy list”), and the names may be categorized into one or more groups. Information describing the on-line presence of the user within the instant messaging system may be disseminated to users of each group based on notification information that is associated with the group. In a similar manner, a user of a mobile communications device, such as a mobile telephone, may store names and telephone numbers in a contact list, and the names may be categorized into one or more groups. 
     Information related to the geographic location of the mobile communications device may be disseminated to users of each group of the contact list based on notification information that is associated with the group. A user interface enables a user to specify how on-line presence information and/or geographic location information should be disseminated to groups. A delegation model is used to control whether modifications to the notification information may be made. 
       FIG. 1  illustrates a communications system  100  capable of controlling dissemination of geographic location or on-line presence information for a user to a communications identity. In general, a geographic location of a user is based on detecting the geographic location of a mobile telephone, a cellular telephone or another device associated with the user, whereas on-line presence of the user is based on detecting that the user has used a computer, a mobile computing device, or another device to sign on to a host system or an instant messaging system accessible through a data network. Information related to a geographic location and an on-line presence of a communications identity collectively may be referred to as notification information. The system  100  enables the user to control the dissemination of notification information, for example, based on the group identity of the communications identity to whom the disclosure of notification information is to be made or a temporal constraint directly or indirectly associated with the communications identity. 
     In particular, the communications system  100  includes a cellular system  110  capable of communicating with an instant messaging system  140  over a telephone network  130  and a data network  170 . The telephone network  130  may be a Public Switched Telephone Network (PSTN) or a Voice Over Internet Protocol (VoIP) network. The cellular system  110  also is capable of communicating with mobile telephones  120   a  and  120   b , respectively, over wireless communication pathways  118   a  and  118   b . When a telephone call occurs between two mobile telephones  120   a  and  120   b , the cellular system  110  routes the telephone call. 
     The cellular system  110  includes geographic location information  112  that includes information on the geographic locations of each of mobile telephones  120   a  and  120   b  that use the cellular system  110 . This may be accomplished, for example, by storing in a data table, list or another type of data collection an association between a unique identifier for each of the mobile telephones  120   a  and  120   b  and the geographic location of the mobile telephone  120   a  or  120   b . A unique identifier for the mobile telephone  120   a  or  120   b , for example, may be the telephone number of the mobile telephone, a mobile electronic identity number (MEIN), a mobile identification number (MIN), a proprietary unique identifier (such as an account identifier), or another type of identifier that uniquely identifies a mobile telephone or a mobile telephone subscriber. 
     The cellular system  110  also is capable of detecting, or receiving indications of, the geographic locations of the mobile telephones  120   a  and  120   b  and storing the geographic locations of the mobile telephones  120   a  and  120   b  in geographic location information  112 . In one example, the geographic location of a mobile telephone  120   a  or  120   b  is received from the mobile telephone  120   a  or  120   b  itself. Additionally or alternatively, the cellular system may detect the geographic location of each of the mobile telephones  120   a  or  120   b . For example, in one implementation, the cellular system  110  uses triangulation based on perceived distance of the mobile telephones  120   a  and  120   b  from multiple elements of the cellular system  110  (e.g., transmission towers) to determine the geographic locations of the mobile telephones  120   a  and  120   b . The perceived distance of the mobile telephones  120   a  and  120   b  is calculated from the time needed for signals from the mobile telephones  120   a  and  120   b  to reach the cellular system  110 . In any case, the cellular system  110  stores the geographic locations of the mobile telephones  120   a  and  120   b  in the geographic location information  112 . 
     The cellular system  110  also includes geographic location notification information  114  that is used to control how the geographic location information  112  is to be disseminated. More particularly, the geographic location notification information  114  specifies communications identities (each of which typically identifies a person) with whom the geographic location information  112  is to be shared or withheld. The geographic location notification information  114  also may identify dates and times during which geographic location information  112  is to be shared or withheld. In addition, the geographic location notification information  114  may identify other conditions that determine how the geographic location information  112  is to be shared or withheld. The other conditions may consider a type of device to which the geographic location information  112  will be sent, or characteristics of users to whom the geographic location information  112  will be sent, when determining how the geographic location information  112  is to be shared or withheld. 
     A user of a mobile telephone  120   a  or  120   b  may control the users with whom the geographic location information for the mobile telephone  120   a  or  120   b  is shared or withheld, except as required by law or government regulation or based on delegation information  116  described later. In one example, the user may specify that the geographic location information for the mobile telephone  120   a  or  120   b  may be shared only at particular time periods or with particularly identified people, such as people identified on a contact list  122   a  or  122   b  associated with the respective mobile telephone  120   a  or  120   b . In some implementations, copies of the contact lists  122   a  and  122   b  also are stored on the cellular system  110 . 
     In some cases, the user&#39;s ability to control with whom the geographic location information is shared or withheld may be restricted by delegation information  116  included in the cellular system  110 . The delegation information  116  may reflect a delegation model that identifies categories of users, and, for each category, identifies particular restrictions on how the geographic location information  112  is to be shared or withheld. For example, the delegation model may indicate that the geographic location information  112  is to be shared with all members of a particular category, regardless of what is, or is not, specified in the geographic location notification information  114 . In one implementation, the categories may form a hierarchy in which lower categories have more restrictions on how the geographic location information  112  is to be shared or withheld than higher categories. In some implementations, the restrictions of the delegation model may override the geographic location notification information  114 . 
     The mobile telephones  120   a  and  120   b  each include a respective contact list  122   a  or  122   b  that includes contact information for people that may be called with the mobile telephones  120   a  or  120   b . For example, the contact list  122   a  or  122   b  may include associations of communication identities and telephone numbers. One example is the association of the communication identity “Mother” (here, a nickname is used rather than a proper name) and a telephone number that may be used to contact the communication identity. The contact list  122   a  or  122   b  enables a mobile telephone user to access contact information for use in displaying the contact information or using the contact information to initiate a telephone call. Not all of the communication identities in the contact list  122   a  or  122   b  are necessarily called with the mobile telephone. Similarly, telephone numbers not included in the contact list  122   a  or  122   b  may be called using the mobile telephone. 
     In some implementations, either or both of the mobile telephones  120   a  and  120   b  may be operable to notify the cellular system  110  of its geographic location. For example, each of the mobile telephones  120   a  and  120   b  may include a respective global positioning system (GPS) receiver  124   a  or  124   b  operable to determine the geographic location of the corresponding mobile telephone  120   a  or  120   b . The geographic location determined using the GPS receiver  124   a  or  124   b  may be transmitted to the cellular system  110  over the respective wireless communication pathway  118   a  or  118   b.    
     The communications system  100  also includes an instant messaging system  140 . The instant messaging system  140  enables users of computers  150   a  and  150   b  to communicate with one another. Users may use one of the computers  150   a  or  150   b  to sign-in (or log-in) to a host system  160  that provides a connection to the data network  170 . In one implementation, the host system  160  is operated by an Internet service provider (ISP) or an Internet access provider and also provides an electronic mail system  162 . Since the instant message system  140  also is connected to the data network  170 , the computers  150   a  and  150   b  are indirectly connected to the instant messaging system  140 . This enables users of the computers  150   a  and  150   b  to communicate using instant messages. Alternatively or additionally, users of the computers  150   a  and  150   b  may connect directly to the data network  170 , and hence to the instant messaging system  140 , without connecting through the host system  160 . The computers  150   a  and  150   b  may be any device that may be used to send and receive communications, such as, for example, a desktop computer, a laptop computer, a personal digital assistant (PDA), or a mobile telephone. In general, presence refers to the availability of a user of a device to communicate using the device. In some implementations, one of the mobile telephones  120   a  and  120   b  and one of the computers  150   a  and  150   b  may be the same device. 
     The instant messaging system  140  includes on-line presence information  141  that includes information on the on-line presence of users. On-line presence of a user refers to the availability of the user to communicate using the instant messaging system  140 . In one example, a user may be designated as “present” when the user has used a computer  150   a  or  150   b  to log in to the instant messaging system  140  and is available to send and receive instant messages. As another example, a user is designated as “present” if the user is using a computer  150   a  or  150   b  and has not been inactive for a predetermined amount of time. If a user has not used the instant messaging system  140  for a particular amount of time, or if the user has explicitly indicated that the user is unavailable to communicate with the instant messaging system  140 , the user may be designated as “not present.” In addition, if a user is communicating and is unable to participate in further communication, the user may be designated as “not present.” For example, a user who is connected to the instant messaging system  140  through a mobile telephone may be designated as “not present” when engaged in a conversation using the mobile telephone if the user is unable to simultaneously participate in instant messaging communication. Signing in to the instant messaging system  140  notifies the instant messaging system  140  of the on-line presence of the user, and the instant messaging system  140  stores that information in the on-line presence information  141 . 
     The instant messaging system  140  includes on-line presence notification information  143  for use in controlling how on-line presence information  141  of an instant messaging user is to be disseminated. More particularly, the on-line presence notification information  143  specifies other users of the instant messaging system  140  with whom the on-line presence information  141  is to be shared or from whom the information  141  is to be withheld. The other users of the instant messaging system  140  may be referred to as communications identities. The on-line presence notification information  143  also may identify dates and times during which on-line presence information is to be shared or withheld. In addition, the on-line presence notification information  143  may identify other conditions that determine how the on-line presence information  141  is to be shared or withheld. The other conditions may consider a type of device to which the on-line presence information  141  will be sent, or characteristics of users to whom the on-line presence information  141  will be sent, when determining how the geographic location information  112  is to be shared or withheld. 
     A user of the instant messaging system  140  may control the users with whom the on-line presence information is shared. For example, the user is to may specify that the on-line presence information for the user be shared with all or a subset of the people on a user-created list of people with whom instant messages are exchanged. The list of people is stored in the participant lists  145  and is commonly referred to as a “buddy list.” 
     In some cases, the user&#39;s ability to control with whom the on-line presence information is shared may be restricted by the delegation information  147 . As with delegation information  116  of the cellular system  110 , the delegation information  147  may be based on a delegation model that identifies categories of users and, for each category, designates restrictions on how the on-line presence information  141  is to be shared or withheld. The delegation model for delegation information  147  may be substantially the same delegation model as is used for delegation information  116  of the cellular system  110 , but it does not necessarily need to be the same or substantially similar. 
     The instant messaging system  140  also may include account linking information  149 . Each user of the instant messaging system  140  holds at least one account with the instant messaging system  140 . When a user logs in to the instant messaging system  140 , the user provides authentication information for one of the corresponding accounts. After the authentication information has been verified, the user appears to be logged in to the instant messaging system  140  through the account. 
     Relationships may be established between the accounts corresponding to the user such that when the user logs in to the instant messaging system  140  with one account, the user appears to be logged in to the instant messaging system  140  through all accounts linked to the account used to log in. In such a case, on-line presence information may be shared for all of the linked accounts. A similar feature may be present for users of the cellular system  110 , in which case multiple accounts with the cellular system  110  are linked and geographic location information is shared for all linked accounts based on the geographic location of one of the linked accounts. In some systems, account information of a mobile telephone owner or user may be linked with one or more instant messaging accounts. Such account or identity linking may enable the control of the dissemination of presence information and geographic location across multiple accounts of various types used by the same person. For example, an account with the electronic mail system  162 , an account with the cellular system  110 , and an account with the instant messaging system held by one person may be linked together. Use of the electronic mail system  162  may lead to the dissemination of geographic location information to other users of the cellular system  110  or the instant messaging system  140 . 
     In some implementations, the geographic location information  112  may be shared with users of the instant messaging system  140 , and the on-line presence information  143  may be shared with users of the cellular system  110 . For example, a user may use both a mobile telephone  120   a  and a computer  150   a  to communicate. While using the computer  150   a  to send and receive instant messages, the user may want to know the geographic location of a person that is identified on the contact list  122   a  of the mobile telephone  120   a . Similarly, the user may want to know the on-line presence of a person with whom instant messages are exchanged with the instant messaging system  140  while using the mobile telephone  120   a . Therefore, the telephone network  130  and the data network  170  are used to allow the cellular system  110  and the instant messaging system  140  to communicate to share geographic location information  112  and on-line presence information  143 . 
     The host system  160  also includes an electronic mail (e-mail) system  162  that may be accessed by users of the computers  150  to send and receive electronic mail. Users of the mobile telephones  120   a  and  120   b  also may access the e-mail system to send and receive electronic mail using the mobile telephones  120   a  and  120   b . More particularly, the mobile telephones  120   a  and  120   b  may access the electronic mail system  162  by using the cellular system  110 , the telephone network  130 , and the data network  170  to access the host system  160  on which the electronic mail system  162  is located. The mobile telephones  120   a  and  120   b  are capable of sending and receiving electronic mail messages using short message service (SMS) or i-mode. SMS and i-mode are protocols by which text messages, such as e-mail messages, may be sent to and from the mobile telephones  120   a  and  120   b.    
       FIGS. 2A and 2B  illustrate one particular implementation of a communications system  200  to show the structure generally included with respect to the communications system  100  of  FIG. 1 . In fact, using the structure and organization shown by  FIG. 1 ,  FIGS. 2A and 2B  provide an illustration of the systems that may be used to implement each of cellular system  110 , telephone network  130 , instant messaging system  140 , and data network  170 . The communications system  200  includes a cellular system  110  that is accessed by one or more mobile telephones  120   a  and  120   b  and is capable of detecting or receiving an indication of the geographic location of each of the mobile telephones  120   a  and  120   b . The mobile telephones  120   a  and  120   b  communicate with the cellular system  110  in order to make and receive telephone calls. 
     More particularly, the cellular system  110  includes base stations  212   a ,  212   b  and  212   c . When either of the mobile telephones  120   a  or  120   b  is turned on, the mobile telephone  120   a  or  120   b  finds the nearest base station  212   a ,  212   b  or  212   c  and establishes a communications link with that base station. For example, the mobile telephone  120   a  establishes a communications link with the base station  212   b  since the base station  212   b  is closest to the mobile telephone  120   a , and the mobile telephone  120   b  establishes a communications link with the base station  212   c  since the base station  212   c  is closest to the mobile telephone  120   b . The process of establishing a communications link with a base station  212   a ,  212   b  or  212   c  is called registration. The base stations  212   a ,  212   b  and  212   c  include antennas, amplifiers, receivers, transmitters, and similar hardware for sending signals to and receiving signals from the mobile telephones  120   a  and  120   b . Each base station may send signals to and receive signals from multiple mobile telephones  120   a  and  120   b . When a user of a first mobile telephone  120   a  places a call to a user of a second mobile telephone  120   b , the first mobile telephone  120   a  communicates with the base station  212   b  with which registration has occurred. More particularly, when the user speaks into the first mobile telephone  120   a , the speech is converted into an analog or digital audio signal that is transferred to the base station  212   b.    
     The base station  212   b  sends the audio signal to a mobile switching center  230 . While only a single mobile switching center  230  is show, the cellular system  110  typically includes more than one mobile switching center  230 . The mobile switching center  230  is responsible for sending signals to and receiving signals from multiple base stations  212   a ,  212   b  and  212   c , but no base station  212   a ,  212   b  or  212   c  communicates with multiple mobile switching centers  230 . The mobile switching center  230  is operable to route the audio signal received from the base station  212   b  that communicates with the first mobile telephone  120   a . Each mobile switching center  230  includes a communications module  231  that determines how the audio signal is to be routed and that sends the audio signal to the appropriate destination. The mobile switching center  230  also includes a short message service module  235  that is similar in function to the communications module  231 . However, while the communications module  231  determines how audio signals are routed, the short message service module  235  determines how text messages are routed between the mobile telephones  120   a  and  120   b.    
     When the second mobile telephone  120   b  communicates with a base station  212   c  that is serviced by the same mobile switching center  230  as the base station  212   b  with which the audio first mobile telephone  120   a  communicates, the mobile switching center  230  simply forwards the audio signal to the base station  212   c , and the base station  212   c  forwards the audio signal to the second mobile telephone  120   b  so that the user of the second mobile telephone  120   b  is able to hear what the user of the first mobile telephone  120   a  said. In contrast, when the second mobile telephone  120   b  and the first mobile telephone  120   a  communicate with base stations that are not serviced by the same mobile switching center  230 , then the mobile switching center  230  sends the audio signal to a gateway mobile switching center  240  for further routing of the call to the appropriate mobile switching center and, subsequently, to the second mobile telephone  120   b.    
     The cellular system  110  includes one gateway mobile switching center  240 . The gateway mobile switching center  240  takes calls from one or more mobile switching centers  230  and routes the calls to the appropriate destination. The gateway mobile switching center  240  includes a communications device  242  that is operable to determine how the calls are to be routed and, based on the determination, to route the calls to the appropriate destination. For example, if the first mobile telephone  120   a  and the second mobile telephone  120   b  are serviced by different mobile switching centers, then a call placed from the first mobile telephone  120   a  to the second mobile telephone  120   b  is routed through the base station  212   b  and a mobile switching center  230  near the first mobile telephone  120   a , through the gateway mobile switching center  240 , through a different mobile switching center  230  and base station  212   c  near the second mobile telephone  120   b , and, finally, to the second mobile telephone  220   b  itself. 
     The gateway mobile switching center  240  also includes a wireless application protocol (WAP) gateway  244 . WAP is a standard with which wireless devices, can access a data network. As such, the WAP gateway  244  provides a route by which the mobile telephones  120   a  and  120   b  can access the data network  170 . For example, when a mobile telephone  120   a  or  120   b  attempts to access the data network  170 , the signal from the mobile telephone  120   a  or  120   b  is routed through one of the base stations  212   a - 212   c , the mobile switching center  230 , and the WAP gateway  244  of the gateway mobile switching center  240  before traveling through the telephone network  130  to reach the data network  170 . 
     When the call from the first mobile telephone  120   a  is placed to a grounded telephone (not shown) connected to the telephone network  130  instead of the second mobile telephone  120   b , the gateway mobile switching center  240  routes the call to the telephone network  130 , and the telephone network  130  routes the call to the grounded telephone. Similarly, when the call from the first cellular system  120   a  is placed to an external cellular system (not shown) that is different from the cellular system  210  used by the first mobile telephone  120   a , the gateway mobile switching center  240  routes the call to the telephone network  130 , the telephone network  130  routes the call to the external cellular system, and the external cellular system routes the call to the final destination. 
     The communications system includes a host system  160  to which computers  150   a  and  150   b  may be connected. Users of the computers  150   a  and  150   b  have accounts with the host system  160 . The users enter information to authenticate the accounts, and the authentication information is verified by a host system login server  272 . If the host system login server  272  verifies the authentication information, then the computer  150   a  and  150   b  are allowed to access the host system  160 . 
     For example, after logging in to the host system  160 , the users may access an electronic mail system  162 . The electronic mail system  162  includes a secure mail transfer protocol (SMTP) server  274  that is used to send messages created by the users of the computers  150   a  and  150   b . Messages sent to the users are stored on a server  275  that implements the post office protocol (POP) or the Internet message access protocol (IMAP). After a user logs in to the host system  160  and accesses the electronic mail system  162 , the user may request to view messages stored on the POP or IMAP server  275 . The messages are transferred from the POP or IMAP server  275  to the computer that the user is using. 
     The electronic mail system  162  also includes a mobile telephone e-mail gateway  276  with which users of the mobile telephones  120   a  and  120   b  may access the electronic mail system  162 . By way of example, when a user of the mobile telephone  120   a  wishes to access the electronic mail system  162 , a connection between the mobile telephone  120   a  and the host system  160  must be established. To do so, the mobile telephone  120   a  accesses the WAP gateway  244  of the gateway mobile switching center  240 , and the WAP gateway  244  provides a connection to the data network  170  to which the host system  160  is connected. The user of the mobile telephone  120   a  logs in to the host system  160  with the host system login server  272 . After logging in, the user of the mobile telephone  120   a  may access the SMTP server  274  and the POP or IMAP server  275  to send and receive electronic mail through the mobile telephone e-mail gateway  276 . 
     After logging in to the host system  160 , users of the computers  150   a  and  150   b  may access an instant messaging system  140 . Similarly, users of the mobile telephones  120   a  and  120   b  may access the instant messaging system  144  through the WAP gateway  244 . The instant messaging system  140  is used to send text-based messages between the users. Each user has an account with the instant messaging system that is authenticated before any instant messages are sent or received by the user. The user uses a computer  150   a  or  150   b  or a mobile telephone  120   a  or  120   b  to enter information to authenticate the account, and the information is sent to an instant messaging login server  281  included in the instant messaging system  140 . The instant messaging login server  281  verifies that the authentication information is correct and enables the user to access an instant messaging server  282 . The instant messaging server  282  facilitates the transfer of messages between users. 
     The geographic locations of the mobile telephones  120   a  and  120   b  may be inferred from the connection of the mobile telephones  120   a  and  120   b  to the cellular system  110 . In one implementation, signals from the mobile telephones  120   a  and  120   b  may be received by multiple base stations  212   a - 212   c . The distance between a mobile telephone  120   a  or  120   b  and the base stations  212   a - 212   c  may be determined from the time needed for a signal to travel from the mobile telephone  120   a  or  120   b  to the base stations  212   a - 212   c , since distance is proportional to the time needed for the signal to travel from the mobile telephone  120   a  or  120   b  to the base station  212   a ,  212   b , or  212   c . Since the geographic locations of the base stations  212   a - 212   c  are known, the geographic location of the mobile telephone  120   a  or  120   b  can be determined based on the distance of the mobile telephone  120   a  or  120   b  from the base stations  212   a - 212   c.    
     More particularly, the mobile telephone is located somewhere on a circle centered at the base station with a radius equal to the distance between the mobile telephone and the base station. When the distance of the mobile telephone from multiple base stations is known, triangulation may be used to more accurately determine the geographic location of the mobile telephone. More particularly, the intersection of the sets of possible locations of the mobile telephone relative to the multiple base stations (i.e., the circles of possible locations of the mobile telephones around the base stations) defines the possible geographic locations of the mobile telephone. When distances from two base stations are known, triangulation results in two possible geographic locations for the mobile telephone. When distances from more than two base stations are known, triangulation results in a single possible determination of the geographic location. 
     In another implementation, a less precise geographic location of the mobile telephone  120   a  or  120   b  is determined by identifying the base station with which the mobile telephone is communicating. Based on this identification, the location of the mobile telephone is designated as being “near” the geographic location of the base station. 
     In yet another implementation, the mobile telephones  120   a  and  120   b  may use the included GPS receivers  124   a  and  124   b , respectively, to determine the location of the mobile telephones  120   a  and  120   b . The mobile telephones  120   a  and  120   b  transfer the geographic location identified with the GPS receivers  124   a  and  124   b  to the cellular system  110  for use. 
     In yet another implementation, the location of the mobile telephones  120   a  and  120   b  may be indicated by users of the mobile telephones  120   a  and  120   b . For example, the users may specify the geographic locations of the mobile telephones  120   a  and  120   b , and the geographic locations may be transferred to and stored in the geographic location information  112 . 
       FIG. 3  illustrates an instant messaging interface  300  with which instant messages may be sent and received. In response to use of the instant messaging interface  300 , notification information may be disseminated in a manner that is controllable by a user of the instant messaging interface  300 . After a sender of instant messages is notified that a recipient is “present” and available to send and receive instant messages, the sender may use the instant messaging interface  300  to exchange instant messages with the recipient. The instant messaging interface  300  includes a message history box  305  that lists the instant messages sent between the sender and the recipient. The message history box  305  also may be referred to as a message transcript box  305 . Each message is presented with an indication of a screen name by which the sender or the recipient is identified as the source of the message. Each message listed in the message history box  305  also includes the text of the instant message sent by the sender or the recipient. For example, the message history box  305  includes a message  306  sent by a user with a screen name “ProductRep” and a message  307  sent by a user with a screen name “Subscriber.” The users that sent the messages  306  and  307  are, respectively, the sender and the recipient. In one implementation, each message listed in the message history box  305  includes a time stamp of when the message was sent. 
     The instant messaging interface also includes a message specification box  310  in which the sender may specify a message to be sent to the recipient. The sender may enter text to be sent to the recipient in the message specification box  310 . The instant message interface  300  includes a set of format controls  315  that may be used to format the text entered in the message specification box  310 . More particularly, the controls in the format controls  315  enable the user to change the size, foreground color, background color, style, and effects of the text entered in the message specification box  310 . The format controls  315  also include controls for inserting objects that are not plain text, such as hyperlinks and emoticons, into the message specification box  310 . 
     After a message has been specified in the message specification box  310 , it may be sent by selecting a send button  318  included in a second set of controls  320 . After the send button  318  has been selected, the text that has been entered in the message specification box  310  is sent to the recipient, the message specification box  310  is cleared, and the message is added to the message history box  305 . The message also is displayed in a message history box  305  of an instance of the instant messaging interface  300  being viewed by the recipient. Also included in the second control set  320  are controls for warning ( 321 ) or blocking ( 322 ) instant messages or adding ( 323 ) the recipient to a participant list maintained by the sender. 
       FIGS. 4A and 4B  are illustrations of participant list interfaces  400 A and  400 B for an instant messaging system that indicate whether the members of a participant list are to receive notifications of geographic location or on-line presence of a user of the participant list interfaces  400 A and  400 B. Each of the participant list interfaces  400 A and  400 B includes a participant list  405 . The people included in the participant list  405  may be separated into one or more groups, and a determination of whether the members of the participant list  405  are sent notifications of geographic location or on-line presence may be specified on a group-by-group basis. For example, the participant list  405  in the participant list interface  400 A includes a group named “Recent Contacts,” and the members of the “Recent Contacts” group receive notifications of geographic location, as evidenced by the geographic location icon  410  next to the heading of the “Recent Contacts” group. Similarly, the participant list  405  in the participant list interface  400 A includes a group named “Family,” and the members of the “Family” group are not to be provided with notifications of geographic location of the user, as evidenced by the negative geographic location icon  415  next to the heading of the “Family” group. 
     Whether the members of the participant list  405  are provided with notifications of the user&#39;s geographic location or on-line presence also may be specified on a member-by-member basis. For example, the participant list  405  in the participant list interface  400 B includes a screen name “Boss.” The member corresponding to the screen name “Boss” is sent notifications of on-line presence of the user, as evidenced by an on-line presence icon  420  next to the screen name “Boss.” Similarly, the participant list  405  in the participant list interface  400 B includes a screen name “SalesRep.” The member corresponding to the screen name “SalesRep” is not sent notifications of on-line presence of the user, as evidenced by negative on-line presence icon  425  next to the screen name “SalesRep.” 
     Entire groups in the participant list  405  also may be provided or explicitly not provided with notifications of on-line presence, and this may be evidenced through the display of an on-line presence icon or a negative on-line presence icon next to one of the group headings in the participant list  405 . Similarly, individual members of the participant list  405  also may optionally be provided with notifications of geographic location, and this may be evidenced through the display of a geographic location icon or a negative geographic location icon next to an individual screen name in the participant list  405 . 
     In addition, individual members of a group may be opted out of the status assigned to the group. For example, in  FIG. 4A , a negative geographic location icon could be used to indicate that “Sales Rep” is not to receive geographic location information even though the “Recent Contacts” group to which “Sales Rep” belongs is authorized to receive such information. Notifications of geographic location or on-line presence may be sent to locations external to the instant messaging system for which the participant list interfaces  400 A and  400 B are displayed. For example, notifications of geographic location may be sent from the instant messaging system to a cellular telephone system. When notifications are sent to an external system, an external system icon  430  is placed next to one of the icons  410  or  420  displayed with the group or screen name to which the notifications are sent. For example, the notifications of geographic location that are sent to the members of the “Recent Contacts” group of the participant list  405  of the participant list interface  400 A are sent to an external communications system. This is evidenced by the external system icon  430  that is displayed next to the geographic location icon  410 . 
     The user may define time periods and may designate the people to whom notifications are sent based on a current time period. The nature and means of specifying the time period is described below with respect to  FIGS. 5 and 6 . The participant list interfaces  400 A and  400 B include an indicator  435  that indicates the time period that is currently occupied. For example, the indicator  435  indicates that a time period that the user has named “Personal Time” is currently occupied. Notifications are sent according to the definition of the “Personal Time” time period. The user may choose to override the notification settings defined for the “Personal Time” time period through selection of an override button  440 . Selecting the override button  440  causes notifications to be withheld because the definition of the “Personal Time” time period calls for notifications to be sent to certain members of the participant list  405 . 
       FIGS. 4C and 4D  illustrate participant list setup interfaces  400 C and  400 D with which the people to whom notifications of geographic location or on-line presence are sent may be specified. Each of the participant list setup interfaces  400 C and  400 D includes a participant list  455  that includes screen names of people with whom instant messages are exchanged using an instant messaging system. Names may be added to and removed from the participant list  455  using the participant list setup interfaces  400 C or  400 D. Names may be separated into groups and groups may be created or removed with the participant list interfaces  400 C or  400 D. 
     Groups or individual users may be selected to receive notifications of on-line presence or geographic location, and the display of icons  460 ,  465 ,  470 , and  475  next to the names of the groups or the individual users indicate if and what kind of notifications are to be received. An external system icon  480  indicates whether notifications for the corresponding group or individual user are sent to an external system. For example, notifications may be sent from the instant messaging system for which the participant list setup interfaces  400 C and  400 D are displayed to a cellular telephone system when the notification settings specify that a user of the cellular telephone system may be sent notification information. The icons  460 - 480  have a similar meaning and interpretation as the icons  410 - 430  of  FIGS. 4A and 4B . 
     The participant list setup interfaces  400 C and  400 D include a setup button  485  that may be selected to enable the specification of notification settings for the people included in the participant list  455 . In one implementation, selecting the setup button  485  displays an interface for specifying notification settings 
       FIG. 5  illustrates a user interface  500  with which settings related to notifications of on-line presence and geographic location may be specified. The notification settings interface  500  enables the specification of dates and times during which notifications of on-line presence and geographic location of a user may be sent to particular people or groups of people with whom communication occurs. The notification settings interface  500  also enables the specification of dates and times during which notifications are not sent to particular people or groups of people with whom the user communicates. The user interface  500  may be implemented on the instant messaging system  140 , the computer  150   a  or  150   b , or the host system  160  of  FIG. 1 . A user of the computer  150   a  or  150   b  may access the user interface  500  from the instant messaging system  140  or the host system  160  if the user interface  500  is not implemented on the computers  150 . The notification settings specified through use of the user interface  500  are stored in the geographic location notification information  114  or on-line presence notification information  143  of  FIG. 1 . 
     Typically, the user using the user interface  500  to enter or raise notification settings is the same user to whom the notification settings apply. However, this is not necessarily so. In some implementations, a user may delegate authorization to another user to modify notification settings on the user&#39;s behalf. For example, a user that is a child may delegate authorization to a parent to modify notification settings on the child&#39;s behalf, and the parent may use the user interface  500  to do so. As another example, users under the jurisdiction of a government may delegate authority to the government to modify notification settings on behalf of the users. As yet another example, an employee may delegate authorization to modify notification settings to an employer. Typically, authorization to modify notification settings is delegated to a user of a higher status. However, the authorization may be delegated to a user of a lower status. For example, a parent may delegate the authorization to a child, a government may delegate the authorization to users under the jurisdiction of the government, or an employer may delegate the authorization to an employee. 
     The notification settings interface  500  includes a participant list window  510  of participant lists maintained by the user. Each participant list includes names of people with whom communication regularly occurs. The communication may be in the form of instant messages and/or mobile telephone calls. The participant list window  510  may be separated into groups, and similar participant lists may be placed in the same group. For example, the participant list window  510  includes three groups  512   a - 512   c . The group  512   a  is for participant lists that include friends, such as a gaming friends participant list  514   a , a college friends participant list  514   b , and a card-playing friends participant list  514   c . Similarly, a family group  512   b  is for of participant lists that include family members, such as an immediate family participant list  514   d  and an in-laws participant list  514   e . Finally a work group  512   c  includes a co-workers participant list  514   f , a clients participant list  514   g , and a managers participant list  514   h.    
     Each of the participant lists  514   a - 514   h  may be a buddy list from an instant messaging system, a contact list of a cellular telephone system, or another list including contact information. In one implementation, the participant lists  514   a - 514   h  may be of mixed types. For example, the participant list  514   a  may be a buddy list from an instant messaging system while the participant list  514   b  may be a contact list from a cellular telephone system. In another implementation, one of the participant lists  514   a - 514   h  may include contact information of multiple types. For example, the participant list  514   c  may include instant messaging screen names and mobile telephone numbers. 
     The groups  512   a - 512   c  and the participant lists  514   a - 514   h  may be expanded and collapsed to display the contents of the groups  512   a - 512   c  and the participant lists  514   a - 514   h . Expanding one of the groups  512   a - 512   c  makes visible the names of the participant lists that are included in the group, while collapsing one of the groups  512   a - 512   c  hides the names of the participant lists that are included in the collapsed group. Similarly, expanding one of the participant lists  514   a - 514   h  makes visible the communications identities included in the expanded list, while collapsing one of the participant lists  514   a - 514   h  hides communications identities included in the collapsed list. Simultaneously expanding and collapsing the groups  512   a - 512   c  and the participant lists  514   a - 514   h  makes visible the hierarchy of communications identifiers. For example, the groups  512   a - 512   c  occupy the top level of the hierarchy, the participant lists  514   a - 514   h  occupy the next lower level, groups within the participant lists  514   a - 514   h  occupy the next level, and the individual communications identifiers within the participant groups occupy the bottom level. Notifications settings may be created for each element in the hierarchy. Notification settings specified for a particular element in the hierarchy apply to all communications identifiers below the element in the hierarchy, unless settings for underlying elements are affirmatively changed. In another implementation, the set of communications identifiers included in the participant lists  514   a - 514   h  may be modeled as a single list without a hierarchical structure. 
     The notification settings interface  500  also includes a notification settings window  520  that displays notification information for an item selected from the participant list window  510 . The item selected from the participant list window  510  may be a group of participant lists, such one of the groups  512   a - 512   c . The item may be an individual participant list from within a group of participant lists, such as one of the participant lists  514   a - 514   h . The item may be a group of communications identities from within a participant list, or the item may be an individual communications identity. The item also may be a combination of groups, participant lists, groups from a participant list, or communications identities. The item may be selected through use of a pointing device or by typing the name of the item to be selected. 
     Here, the work group  512   c  has been selected from the participant list window  510 , and information from the notification settings window  520  applies to all communications identities identified in the participant lists  514   f - 514   h . The notification settings window  520  includes a settings list  530  with multiple settings  532 - 538  that specify different dates and times during which notifications are or are not sent to all communications identities identified in the participant lists  514   f - 514   h . For example, the setting  532  specifies that no notifications are to be sent all day on Sunday, because the setting  532  is listed as private. Similarly, the setting  534  indicates that no notifications are to be sent from 6 P.M. to midnight on Friday, and the setting  536  indicates that no notifications are to be sent all day on Friday, Nov. 27, 2003. The setting  538  currently does not specify a temporal period during which notification information is to be sent or withheld. 
     More particularly, each of the settings was created through use of a create setting window  540 . All of the settings  532 - 538  are initially unspecified. Selection of one of the settings  532 - 538  displays a create setting window  540 . The create setting window  540  includes a setting type option  541 . Setting the setting type option  541  to “notify” indicates that notifications are to be sent during the date and time specified with the notification setting tool  540 . On the other hand, setting the setting type option  541  to “private” indicates that notifications are not to be sent during the date and time specified with the notification setting tool  540 . When the create setting window  540  was displayed for the settings  532 ,  534 , and  536 , the setting type option  541  was set to “private.” In one implementation, the setting type option has a default value of “notify.” In another implementation, the setting type option has a default value of “private.” 
     A starting date and time of the period during which the setting being specified with the create setting window  540  is to be applied may be specified. A date on which the time period begins may be specified in a start date field  543 . In one implementation, the start date field  543  is used to specify a particular month, day, and year on which the time period is to begin. For example, when the create setting window  540  was displayed for the setting  536 , the date “Nov. 27, 2003” was specified in the start date field  543 . In another implementation, the start date field  543  is used to specify days of the week on which the time period is to begin. For example, when the create setting window  540  was displayed for the settings  532  and  534 , the days “Sunday” and “Friday,” respectively, were specified. When a day of the week is specified in the start date field  543 , then the corresponding setting applies each week, beginning on the day specified in the start date field  543 . In another implementation, more complicated repetitions, such as once a month, may be specified with the start date field  543 . 
     A starting time of the period during which the setting being specified with the create setting window  540  is to be applied may be specified with a start time field  545 . The start time field  545  may be used to specify an hour and minute at which the setting is to take effect. For example, when the create setting window  540  was displayed for the setting  534 , the time 6:00 P.M. was specified in the start time field  545 . More abstract times, such as “morning,” “evening,” or “all day” may be specified in the start time field. For example, the setting “all day” was selected from the start time field when the create setting window  540  is displayed for the settings  532  and  536 . 
     An ending date and time of the period during which the setting being specified with the create setting window  540  is to be applied may be specified in an end date field  547  and an end time field  549 , respectively. The end date field  547  is similar to the start date field  543  in the information that it may be used to specify-. The information may be a specific month, day, and year on which the time period during which the corresponding setting applies is to end. For example, when the create setting window  540  was displayed for the setting  536 , the date “Nov. 27, 2003” was specified in the end date field  547 . In one implementation, the value of the end date field  547  is set to the value specified in the start date field  543  once a value has been specified in the start date field  543 . In another implementation, the end date field  547  is used to specify a day of the week on which the time period is to end. For example, when the create setting window  540  was displayed for the settings  532  and  534 , the days Sunday and Friday, respectively, were specified. When a day of the week is specified in the end date field  547 , then the corresponding setting applies each week, ending on the day specified in the end date field  547 . In another implementation, more complicated repetitions, such as once a month, may be specified with the start date field  547 . 
     An ending time of the period during which the setting being specified with the create setting window  540  is to be applied may be specified with an end time field  549 . The end time field  549  may be used to specify an hour and minute at which the setting is to stop taking effect. For example, when the create setting window  540  was displayed for the setting  534 , the time “12:00 A.M.” was specified in the end time field  549 . When an abstract time, such as “morning,” “evening,” or “all day” has been specified in the start time field  545 , then the end time field  549  may be set to the same abstract time. 
     The user interface  500  includes a scope window  550 , and the options within the scope window  550  determine the type of notifications to be sent or withheld from the communications identities corresponding to the item selected from the participant list window  510 . Options  552  and  554  determine whether the settings  532 - 538  in the settings list  530  are applied to geographic location notifications and/or on-line presence notifications. More particularly, selecting a geographic location option  552  causes the entries  532 - 538  in the settings list to be applied to geographic location notifications. Similarly, selecting an on-line presence option  554  causes the entries  532 - 538  in the settings list to be applied to on-line presence notifications. The setting of one of the options  552  or  554  does not affect the setting of the other option  552  or  554 , though both options may be set. 
     The notification settings interface  500  includes an override option  560  that may be selected to allow the current notification settings to override any other notification settings that have been specified for the communications identities corresponding to the item selected in the participant list window  510 . For example, a user may wish to always provide notification information to a spouse, so the user may select the override option  560  and specify a setting in the setting list  530  that dictates that the spouse is always provided with notification information. In this case, the setting to always provide the spouse with notification information overrides any other settings that control how notification information is disseminated to the spouse. As another example, a user may specify that no notification settings are to be sent during the weekend, but a client may wish to be provided with notification information during a particular weekend. In such a case, the user may create a notification setting that dictates that the client is to be sent notification information over the particular weekend and that overrides any other settings for the client. In one implementation, the system is configured to detect notification overrides that conflict with one another, and to permit the user to resolve the conflict. 
     In some implementations, the granularity of the geographic location disseminated may be controlled with the user interface  500 . In such implementations, the user interface  500  includes a geographic location granularity window  570 . Included in the geographic granularity window  570  is a series of mutually exclusive options  571 - 576 . Each of the options  571 - 576  corresponds to a certain level of granularity in the geographic location information that may be transmitted as a result of the notification settings in the notification settings list  530 . The most detailed geographic location information is provided when the street address option  571  is selected. Selecting the city option  572  provides geographic location information to the level of the city currently occupied, but the location within the city is not provided. Selecting the metropolitan area option  573  provides geographic location information to the level of the metropolitan area currently occupied, but the location within the metropolitan area is not provided. Selecting the area of a metropolitan area option  574  provides geographic location information to the level of the area within a metropolitan area currently occupied, but the location within the area of the metropolitan area is not provided. Selecting the region  575  provides geographic location information to the level of the region of a country currently occupied (e.g., the state), but the location within the region is not provided. Selecting the country  575  provides geographic location information to the level of the country currently occupied, but the location within the country is not provided. 
     The user interface  500  enables the easy entry and specification of notification settings. A user of the user interface  500  may quickly select and specify notification settings to be applied to many communications identities. This minimizes the burden of entering and revising notification settings. 
       FIG. 6A  illustrates a calendar interface  600  that may be used to specify dates and times during which notifications of on-line presence and geographic location are and are not to be sent. The calendar interface  600  displays one week, and a user of the calendar interface  600  may create and select time slots  605 - 625  in which to specify how notifications are sent. The time slots  605 - 625  may be created to group periods of time during which notification settings are the same, thereby minimizing the amount of configuration performed by the user. 
     For example, the calendar interface  600  includes a work time slot  605  that covers the hours from 7 A.M. to 6 P.M. on Monday through Friday. The calendar interface  600  includes a first personal time slot  610  that covers the hours from 7 P.M. to 10 P.M. from Monday through Saturday. A second personal time slot  615  covers the time between approximately 2 P.M. to 10 P.M. on Sunday. A private time slot  620  covers the time between 7 A.M. and approximately 1 P.M. on Sunday. Finally, the calendar interface  600  includes an open time slot  625  between 7 A.M. and 6 P.M. on Saturday. 
     In order to specify how notifications are to be sent, participant lists may be associated with the time slots  605 - 625 . Referring also to  FIG. 6B , an association  650  relates participant lists to the time slots  605 - 625 . The association  650  includes a list  655  of participant lists and a list  660  of time slots. Each of the time slots  605 - 625  that is included in the list  660  corresponds to one of the time slots  605 - 625  of  FIG. 6A  and is associated with a set of notification settings. Notification settings of each of the time slots  605 - 625  apply to the participant lists associated with the time slot. For example, since the participant list named “Co-Workers” is associated with the work time slot  605 , the notification settings corresponding to the work time slot  605  are applied to the communications identities included in the “Co-workers” participant list. As another example, since the participant lists named “Gaming Friends” and “Card-playing Friends” are associated with the first personal time slot  610 , the notification settings corresponding to the first personal time slot  610  are applied to the communications identities included in the “Gaming Friends” and “Card-playing Friends” participant lists. In addition to having full participant lists associated with the time slots  605 - 625 , individual communications identities may be specified to obey or override the notification settings corresponding to the time slots  605 - 625 . For example, a communications identity named “spouse” has been associated with and selected to override the notification settings corresponding to the work time slot  605 . 
     In another implementation, names of participant lists may be dragged with a mouse from a list of participant lists that is similar to the participant list window  510  from  FIG. 5  to one of the time slots  605 - 625  to create an association between the participant lists and the time slots  605 - 625 . Dragging and dropping the name of a participant list over a time slot may indicate that the people included in the participant list are (or are not) to be sent notifications of on-line presence or geographic location during the period of time corresponding to the time slot. A secondary action, such as pressing and holding a key on a keyboard, may be used in addition to the dragging and dropping of participant list names with the mouse to specify whether the people included in the participant lists being dragged and dropped are or are not to be sent notifications. In another implementation, selecting one of the time slots  605 - 625  may display a tool for specifying the participant lists that are and are not to be sent notifications during the selected time slot. 
       FIG. 7  is a flow chart of a process  700  for indicating how notification information of geographic location and/or on-line presence is to be disseminated. The process  700 , for example, may be executed by a process of a computer displaying the notification settings interface  500  from  FIG. 5  or the calendar interface  600  from  FIG. 6  for specifying how notifications of geographic location or on-line presence are to be shared. 
     The process  700  begins with the receipt of an indication of a participant list (step  705 ). The participant list includes the names of people with whom instant messages are exchanged. The list may be divided into one or more groups, with each group including one or more names. The people included in the participant list are the people to whom the notification settings created as a result of the execution of the process  700  apply. 
     The processor then receives an indication of a notification setting that identifies a type of setting, a start date and time, and an end date and time (step  710 ). By way of example, the processor may receive the indication of a notification setting from the user interfaces  500  or  600 . 
     The notification setting has one of two types: notify and private. The notification setting also specifies a period of time. When the notification setting type is notify, notification information is provided during the period of time. When the notification type is private, notification is withheld during the period of time. In one implementation, the notification setting has a default type of private, so private notification settings do not need to be specified explicitly. In another implementation, the notification setting has a default type of notify, so notification settings of that type do not need to be specified explicitly. 
     An indication that the notification setting is to apply to geographic location information and/or on-line presence information is received (step  715 ). The indication also may be received from the user interface  500  or  600 . 
     When delegation information is accessible to the processor, the processor makes a determination as to whether a user of the interface  500  or  600  is authorized to create or modify a notification setting for the chosen person based on a delegation model (step  720 ). For example, the processor may access the delegation information  116  or  147  of  FIG. 1  to determine whether the user of the interface  500  or  600  is authorized to create or modify the notification setting. The delegation model separates the communications identities included in the participant list into multiple categories and indicates how the user may create or modify notification settings for each category. For example, the delegation model may create a hierarchy from the people included in the participant list, and the user may belong to one of the levels of the hierarchy. The user may be prevented from modifying the notification settings corresponding to higher levels in the hierarchy. The user also may be allowed to freely create and modify notification settings corresponding to an equal or lower level of the hierarchy. The user is only allowed to create or modify the notification setting as indicated when permitted by the delegation model (step  725 ). 
     If allowed by the delegation model, the notification setting is persistently stored (step  730 ). The notification setting also is sent to an appropriate communications system based on the communications system to which the notification setting is to apply (step  735 ). For example, if the notification setting is to apply to geographic location notifications, then the notification setting is sent to a cellular telephone system. Similarly, if the notification system is to apply to on-line presence notifications, then the notification is sent to an instant messaging system. 
     The process  700  also may be used to specify notification settings that are to apply to parts of the received participant list. For example, notification settings may be specified for individual communications identities within the participant list or for groups of communications identities within the participant list. In such an implementation, the processor receives an indication of the parts of the participant list to which the notification settings are to apply in addition to the indication of the participant list itself. Furthermore, the process  700  also may be used to specify notification settings for communications identities not part of the received participant list. In such an implementation, the processor receives an indication of the communications identities instead of an indication of the participant list. 
       FIG. 8  is an illustration of a delegation model  800  that aids in the determination of how notification setting information corresponding to a user may be specified or modified. The delegation model  800  separates notification settings and users into three categories  805 - 815 , and members of each category are allowed to modify the notification setting information in a particular way. The three categories  805 - 815  of the delegation model  800  collectively form a hierarchy. Members of the top category  805  of the hierarchy are given the most freedom to modify the notification setting information, while members of the bottom category  815  are given the least freedom to modify the notification setting information. More particularly, a member of a given category of the delegation model  800  is allowed to modify notification settings corresponding to the categories of the hierarchy equal to or lower than the category of the member. 
     Notification settings corresponding to the top category  805  of the delegation model are based on government regulations. For example, a notification setting from the top category  805  may enable the full-time disclosure of geographic location to essential services and applications, such as emergency services. A typical user is not allowed to create or change a setting that is not in conformance with government regulations because the typical user does not correspond to the top category  805  of the delegation model  800 . In one implementation, the typical user may be prevented from making changes to the notification settings corresponding to the top category  805  by preventing access to the notification settings from the top category  805 . In another implementation, the notification settings from the top category  805  may override any other settings that are created by the user. 
     Members of the middle category  810  may create notification settings for equipment owners. Equipment owners are people that provide access to a mobile communications device or an instant messaging system to users. Examples of equipment owners are employers and parents, and examples of users are employees and children. Members of the middle category  810  may modify any notification settings that do not pertain to government regulations. For example, members of the middle category  810  may modify settings that define the terms of a usage agreement held between the equipment owner and the user. 
     Members of the bottom category  815  may modify any other notification settings that do not fall within the jurisdiction of the other two categories  805  and  810 . The user himself may be a member of the bottom category  815  and may modify any notification settings that do not correspond to a superordinate category of the delegation model  800 . 
     As an example, the notification settings for a mobile communications device used by an employee and owned by an employer may include a notification setting corresponding to the middle category  810  that dictates that the geographic location of the device must be made available during business hours or at any time. The notification setting corresponds to the middle category  810  because it defines a usage agreement between the employee and the employer. The employee, a member of the bottom category  805 , is not allowed by the delegation model to modify the notification setting corresponding to the middle level  810 . Therefore, the geographic location of the mobile communications device is provided as specified by the notification settings corresponding to the middle category  810 . However, the employee may specify other notification settings that pertain to, for example, whether the geographic location is provided to the user&#39;s family, which correspond to the bottom category  815 . 
     As another example, the notifications for a mobile communications device used by a child and owned by a parent may include a notification setting corresponding to the middle category  810  and specifying that the geographic location of the device is to be made available at all times so that the parent may always know the geographic location of the child. The notification setting corresponds to the middle category  810  because it defines a usage agreement between the child and parent. The child, a member of the bottom category  805 , is not allowed by the delegation model to modify the notification setting corresponding to the middle category  810 . Therefore, the geographic location of the mobile communications device is provided as specified by the notification settings corresponding to the middle category  810 . However, the child may specify other notification settings that pertain to, for example, the child&#39;s friends, which correspond to the bottom category  815 . 
     Alternatively or additionally, a delegation model may separate notification settings and users into categories based on characteristics of users. For example, the delegation model may include a category for users who satisfy a condition and a category for users who do not satisfy the condition. For example, the condition may differentiate between employees of a company and other users. The two categories specified by the condition may be used to specify how notification setting information may be changed. 
       FIG. 9  is a flow chart of a process  900  for modifying notification setting information based on a delegation model, such as the delegation model  800  of  FIG. 8 . The delegation model is used to determine if the modifications to the notification settings are permissible. The process  900  begins when a delegation model is accessed (step  905 ) and a new or modified notification setting is received (step  910 ). 
     A level of the delegation model corresponding to the notification setting that is being modified is identified (step  915 ). For example, using the delegation model  800 , if the received notification setting corresponds to a government regulation, then the top level  805  of the delegation model  800  is identified. A level of the delegation model corresponding to the person that created or modified the received notification setting is identified (step  920 ). For example, if the notification setting is received from an employer of a person to which the notification setting is to apply, then the middle level  810  of the delegation model  800  is identified. 
     Based on the identified levels of the delegation model for the notification setting and its creator, the new or modified notification setting is permitted or disallowed (step  925 ). More particularly, if the level of the person who created or modified the notification setting is higher than or equal to the level of the notification setting that is being modified, then the notification setting is permitted. However, if the level of the person who created or modified the notification setting is lower than the level of the notification setting that is being modified, then the notification setting is disallowed. 
       FIG. 10  is a flow chart of an exemplary process  1000  for providing notification information corresponding to a communications identity. The communications identity may be an instant messaging identity or a mobile telephone. The notification information may be on-line presence information for an instant messaging system or geographic location of a mobile telephone. The process  1000  includes accessing notification setting information corresponding to a communications identity that includes at least one temporal condition that specifies a time period during which notification information is to be provided or withheld (step  1005 ). A determination is made as to whether the temporal condition is satisfied (step  1010 ). In other words, a determination is made as to whether the current time and date are within the time period of the temporal condition. 
     In response to the determination, the dissemination of notification information relating to the communications identity is controlled (step  1015 ). For example, if the temporal condition is satisfied and the notification setting information indicates that notification information is to be provided, then notification information is provided. Likewise, if the temporal condition is satisfied and the notification setting information indicates that the notification information is to be withheld, then the notification information is withheld. On the other hand, if the temporal condition is not satisfied, then the notification setting information is not applied. 
     Withholding notification information includes not disseminating notification as well as preventing other users from obtaining the notification information. For example, if the notification setting information indicates that notification information is to be withheld, then incoming communications associated with the communications identity may be detected, and the communications identity may be alerted to the incoming communications. The incoming communications may be attempts to determine the notification information of the communications identity, such as the online presence or the geographical location of the communications identity, and such attempts to determine the notification information may be denied. 
     When notification information is to be withheld, participant lists that include the communications identity are passively configured such that the participant lists persistently conceal the status of the communications identity. For example, the participant lists may be configured to indicate that the communications identity is not available to communicate. As another example, the participant lists may be configured to indicate that availability information for the communications identity is unknown. Alternatively or additionally, the participant lists may be configured to indicate that the communications identity is not logged onto an instant message system used by the communications identity even when the communications identity actually is logged onto the instant message system Sending a message while notification information is withheld reveals the ability to communicate. If an attempt is made to send a message from the communications identity when the temporal condition is satisfied and the notification setting information indicates that notification information is to be withheld, a prompt may be displayed to alert the communications identity that the availability of the communications identity to communicate will be revealed when the message is sent. 
       FIGS. 11A and 11B  show a process  1100  for transmitting a notification of geographic location of a mobile telephone. Execution of the process  1100  also may result in the optional display of the geographic location of the mobile telephone on instant messaging participant lists. The process  1100  involves a mobile telephone  1105 , a base station  1110 , a mobile switching center  1115 , and an instant messaging system  1120 . The mobile switching center  1115  combines the functionality of the mobile switching center  230  and the gateway mobile switching center  240  of  FIG. 2A  in that the mobile switching center  1115  can both route mobile telephone calls and access the instant messaging system  1120 . 
     The process  1100  begins when the mobile telephone  1105  performs a registration process with the base station  1110  (step  1125 ). After the mobile telephone  1105  has registered with the base station  1110 , the mobile telephone is permitted to place calls through the base station. To do so, the mobile telephone  1105  transmits information to the base station  1110 , which in turn transmits the information to the mobile switching center  1115  (step  1130 ). The mobile switching center  1115  receives the signal from the base station  1110  regarding the mobile telephone  1105  (step  1135 ). 
     The mobile switching center  1115  uses the information received from the base station  1110  to determine the geographic location of the mobile telephone (step  1140 ). Each mobile switching center  1115  receives signals from multiple base stations  1110 , and each base station  1110  covers a particular geographic area. By determining the base station  1110  from which the information was received, the mobile switching center  1115  determines the general geographic location of the mobile telephone  1105 . In another implementation, the distance that the information traveled from the mobile telephone  1105  to a base station  1110  may be determined from the time taken for the information to travel from the mobile telephone  1105  to a base station  1110 . When the distance to one base station  1110  is determined, the geographic location of the mobile telephone  1105  may be specified to a point on a circle centered at the base station  1110  with a radius equal to the distance traveled by the information. When the distance to two base stations  1110  is determined, triangulation may be used to identify two possible locations of the mobile telephone  1105 . When the distance to greater than two base stations  1110  is determined, triangulation may be used to identify the exact location of the mobile telephone  1105 . In another implementation, the mobile telephone  1105  includes a GPS receiver that may be used to determine the geographic location of the mobile telephone  1105 . 
     The geographic location of the mobile telephone  1105  is updated by the mobile switching center  1115  in a home location register (step  1145 ). The home location register stores the geographic location of all mobile telephones  1105  that communicate with the mobile switching center  1115 . 
     The mobile switching center  1115  accesses notification settings associated with the mobile telephone  1105  (step  1150 ). The notification settings indicate how the determined geographic location of the mobile telephone  1105  is to be disseminated. The mobile switching center  1115  determines whether the notification settings indicate that the geographic location of the mobile telephone  1105  should be shared (step  1155 ). To do so, the mobile switching center  1115  determines if the temporal conditions of the notification settings are satisfied. The mobile switching center  1115  also determines if the notification settings indicate that the geographic location is to be shared or kept private during the specified time periods. 
     If the notification settings indicate that the geographic location should be disseminated, then the mobile switching center  1115  permits access to or transmission of the geographic location of the mobile telephone  1105  (step  1160 ). Otherwise, the mobile switching center  1115  does not permit access to or transmission of the geographic location of the mobile telephone  1105  (step  1165 ). 
     If the notification settings indicate that the geographic location should be disseminated, then the mobile switching center  1115  also may send the geographic location of the mobile telephone  1105  to the instant messaging system  1120  (step  1170 ). The instant messaging system  1120  receives the geographic location of the mobile telephone  1105  (step  1175 ). The instant messaging system  1120  then determines an instant messaging identity associated with the mobile telephone  1105  (step  1180 ). In one implementation, the instant messaging system  1120  maintains a table of mobile telephone numbers and instant messaging identities that may be used to determine the instant messaging identity associated with the mobile telephone  1105 . The instant messaging system  1120  accesses a participant list and notification settings associated with the instant messaging identity (step  1185 ). 
     When the notification settings indicate that instant messaging identities on the participant list are to be notified of the geographic location of the mobile telephone  1105 , then the granularity of the geographic location to be provided to the instant messaging identities is determined (step  1190 ). For example, as discussed above, the granularity of the geographic location may be a street address, a city, a metropolitan area, an area of a metropolitan area, a region of a country, or a country. The instant messaging system  1120  may permit the instant messaging identity to which the geographic location applies or a recipient of the geographic location to control the granularity of the geographic location. In such cases, the instant messaging system  1120  determines the appropriate granularity for the geographic location from the settings specified by the IM identity or the recipient. The instant messaging system  1120  also sends the appropriate level of geographic location information for the instant messaging identity corresponding to the mobile telephone  1105  to the instant messaging identities on the participant list (step  1195 ). 
       FIG. 12  illustrates a process  1200  for transmitting a notification of on-line presence. The process  1200  involves a client system  1205 , a host system  1210 , and an instant messaging system  1215 . In one example, the client system  1205  may be an implementation of computer  150   a  or  150   b  of  FIG. 1  that includes software for accessing the host system  1210 . The process  1200  begins when a user of the client system  1205  begins a sign-on and authentication process with the host system  1210  (step  1220 ). The host system  1210  provides the user of the client system  1205  with access to a network on which the instant messaging system  1215  is located. The user of the client system  1205  may then log into the instant messaging system  1215 . The user is identified on the instant messaging system by a unique screen name. The instant messaging system  1215  determines participant lists associated with the screen name of the user (step  1225 ). 
     The instant messaging system  1215  sends the client system  1205   a  list of communications identities on participant lists associated with the user with indications of whether the communications identities are on-line (step  1230 ). The client system  1205  receives the participant lists with the corresponding indications of whether the included communications identities are on-line (step  1235 ). The client system  1205  sends an acknowledgement of the list of communications identities (step  1240 ), which is received by the instant messaging system  1215  (step  1245 ). 
     The instant messaging system  1215  accesses notification setting information associated with a participant list associated with the user of the client system  1205  (step  1250 ). The notification setting information includes at least one temporal condition, and a determination is made as to whether the temporal condition is satisfied (step  1255 ). If so, the instant messaging system informs any communications identity on the participant list for which the notification information was accessed that the communications identity corresponding to the user of the client system  1205  is on-line (step  1260 ). 
     The instant messaging system  1215  also accesses notification setting information associated with the communications identity corresponding to the user of the client system  1205  (step  1265 ). A determination is made as to whether the temporal condition of the notification setting information is satisfied (step  1270 ). If so, the instant messaging system informs any communications identity that includes the communications identity corresponding to the user of the client system  1205  on a participant list that the communications identity corresponding to the user is on-line (step  1275 ). 
     If the temporal conditions associated with the notification setting information corresponding to the participant list or to the communications identity of the user of the client system  1205  is not satisfied, then the temporal condition is monitored until satisfied. When the temporal condition becomes satisfied, appropriate action to provide or withhold notification information is taken (step  1280 ). 
       FIG. 13  is a flow chart of a process  1300  for overriding notification settings. The process  1300  may be performed by a processor in the cellular system  110  of  FIG. 1  in response to the detection of the registration process of a mobile telephone the cellular system or by a processor in the instant messaging system  140  of  FIG. 1  in response to the sign-on of a user to the instant messaging system. The registration process or the sign-on of a user establishes a communications identity that is used to access the cellular system or the instant messaging system. The process  1300  begins when notification settings associated with the communications identity are accessed (step  1305 ). The notification settings include a temporal condition for controlling whether the availability of the communications identity to communicate is disclosed. For example, the temporal condition specifies periods of time during which the availability of the communications identity to communicate with the cellular system or the instant messaging system is disclosed or withheld. 
     The processor makes a determination as to whether the temporal condition is met (step  1310 ). A result of whether the temporal condition is satisfied is displayed on a user device associated with the communications identity (step  1315 ). For example, if the communications identity is communicating with a mobile telephone, the result of the determination may be displayed on a screen included in the mobile telephone. If the communications identity is communicating with the instant messaging system, then the result may be displayed on a display of the computer used to access the instant messaging system. A name for the period of time specified by the temporal condition may be displayed on the user device associated with the communications identity. 
     A message asking whether the user would like to override the notification setting is displayed, and a response to the message is received (step  1320 ). When the response indicates that the communications identity would like to override the notification setting, appropriate action is taken (step  1325 ). For example, the availability of the communications identity to communicate may be provided or withheld regardless of whether the temporal condition is met. More particularly, if the notification setting indicates that the availability is to be withheld, then overriding the notification setting may include providing the availability. Similarly, if the notification setting indicates that the availability is to be provided, then overriding the notification setting may include withholding the availability. Overriding the notification information may include replacing or modifying the notification information to reflect how the user would like the notification information to be disseminated. 
     In one implementation, a new notification setting that specifies the manner in which the availability of the communications identity is provided or withheld to override the existing notification setting may be created, and the new notification setting may permanently replace the existing notification setting. In one such implementation, the new notification setting may be applied during the same temporal period of the existing notification setting, or the new notification setting may be applied at all times. In this manner, the notification setting information may be easily changed. 
     A user may maintain multiple identities between which relationships have been created. The multiple identities may be for a single system, such as with an instant messaging system, an e-mail system, or a cellular telephone system, or the multiple identities may be for multiple systems. For example, a user may maintain an identity with a cellular telephone system, an instant messaging system, and an e-mail system, and all of the identities may be linked together. When identities are linked, the on-line presence or geographic location of one identity applies to all of the identities to which the one identity is linked. Furthermore, the notification settings for the linked identities are collectively used to control the dissemination of the notification information of the linked identities. A first identity that is linked to a second identity may be referred to as an alias of the second identity. 
     Referring to  FIGS. 14A and 14B , seven identities  1402 - 1414  have been linked together using different relationships between pairs of directly linked accounts. The type of relationship used to directly link a pair of identities determines whether a different pair of identities may be indirectly linked. For example, a bi-directional link exists between the identities in  FIG. 14A . A bi-directional link is a two-way link such that linking a first identity to a second identity means that the second identity also is linked to the first identity. Therefore, two relationships are created with a single link. When two identities are linked, notification settings corresponding to the two linked identities are used to control dissemination of the common geographic location of the linked identities. 
     Specifically, in  FIG. 14A , each link is a bi-directional link, and SN 1  is directly linked to SN 2 , SN 3 , SN 4 , and SN 5 . Thus, when SN 1  is used communicate using a communications system, SN 2 , SN 3 , SN 4 , and SN 5  appear as aliases of SN 1 . SN 2  is linked to SN 1  and SN 7 , which appear as aliases of SN 2  when SN 2  is used to communicate using the communications system. Each of SN 3 , SN 4  and SN 5  is linked to SN 1 , which means that SN 1  appears as an alias of SN 3 , SN 4  or SN 5  when SN 3 , SN 4  or SN 5  is used to communicate using the communications system. SN 6  is linked to SN 7 , which appears as an alias of SN 6  when SN 6  is used to communicate using the communications system. Finally, SN 7  is linked to SN 2  and SN 6 , which appear as aliases of SN 7  when SN 7  is used to communicate using the communications system. 
     In  FIG. 14B , one-way linking is used between identities, so a reflexive relationship does not necessarily exist between two linked identities. For two identities to appear linked to one another, each identity has to create a link to the other identity. Specifically, in the example, SN 1  is linked to SN 3 , SN 4 , and SN 5 , which appear as aliases of SN 1  when SN 1  is used to communicate using the communications system. SN 2  is linked to SN 1 , and SN 1  appears as an alias of SN 2  when SN 2  is used to communicate using the communications system. SN 3 , SN 4 , and SN 5  are not linked to any other identities and do not have any aliases. SN 6  is linked to SN 7 , so SN 7  appears as an alias of SN 6  when SN 6  is used to communicate using the communications system. SN 7  is linked to SN 2 , which appears as an alias of SN 7  when SN 7  is used to communicate using the communications system. 
     The description provided above with respect to  FIGS. 14A and 14B  is premised on the identities  1402 - 1414  being linked using a star linking scheme, which dictates that a direct link must exist between two identities before the identities are linked. On the other hand, two identities may appear to be linked even though a direct link between the two identities does not exist. This linking scheme, called mesh linking, calls two identities linked if there is an indirect link between the two identities. For example, in  FIG. 14B , SN 2  and SN 4  may be called linked under a mesh linking scheme because they are indirectly linked through SN 1 . In general, two identities may be called linked in a mesh-linking scheme if there exists a path of linked identities between the two identities. 
       FIG. 15  is a flow chart of a process  1500  for sending notifications of geographic location for multiple linked identities. The process  1500  begins when a notification of geographic location is sent for a first identity (step  1505 ). Other identities to which the identity is linked are identified (step  1510 ). Because the linked identities are linked to the first identity and the first identity is being used, the linked identities also are being used. Therefore, notifications of the geographic location of the linked identities may need to be sent for the linked identities. Notification setting information is accessed for the linked identities (step  1515 ), and a determination is made as to whether notifications of geographic location are to be sent for the linked identities (step  1520 ). For example, temporal conditions of the notification setting information may be checked to determine if notifications are to be sent for the linked identities. Notifications of on-line presence or geographic location are sent to users that include the linked identities on a participant list or to users on participant lists corresponding to the linked identities (step  1525 ). 
     By way of example, a user may maintain two identities, SN 1  and SN 2 , and the identities SN 1  and SN 2  may be linked. The user may be communicating with the identity SN 2 , and notification information may be projected for the identity SN 2  based on notification settings maintained for the identity SN 2  (step  1505 ). The identity SN 1  is identified as linked to the identity SN 2  (step  1510 ). Since the identity SN 1  is linked to the identity SN 1 , the geographic location of the identity SN 2  also applies to the identity SN 1 . Notification information corresponding to the identity SN 1  is accessed (step  1515 ). If it is determined that notification of geographic location should be sent according to the notification settings corresponding to the identity SN 1  (step  1520 ), then the notifications of the geographic location corresponding to the identity SN 1  are permitted (step  1525 ). 
     Mobile telephones communicating with a cellular system are used throughout as examples of mobile communications devices whose geographic location may be determined and disseminated. In general, geographic locations of any mobile communications or computing device, such as a laptop computer, a PDA, or a mobile telephone, may be determined and disseminated to indicate the locations of the users. The geographic location of a mobile communications or computing device may be determined from the device itself, from access points (e.g. cellular system base stations or wireless access points) used by the device, or from explicit user declaration. 
     Similarly, computers and an instant messaging service are used as examples of communications devices and communications services that may be accessed by the communications devices. Use of a communications device to access the communications service indicates the availability of a user of the communications device to communicate, or the presence of the user. Another example of a communications device and a communications service are a mobile telephone and a cellular system. Use of the mobile telephone may both indicate the presence of a user of the mobile telephone and the geographic location of the user. 
     Users of the mobile communications devices and the communications devices may be people or machines under the control of people. For example, a communications device may be configured to communicate with a communications service without explicit use by a person, though the person may control how the communications device communicates with the communications service, and presence and geographic location for the communications device may be disseminated. For example, a mobile telephone may communicate with a cellular system without explicit use by a person to ensure that calls are properly routed, and such communication may be used for determining and disseminating the presence and the geographic location of the person. As another example, presence information and the geographic location of a system for automatically sending and receiving instant messages, which is known as an instant messaging robot or a bot, may be controlled and disseminated. 
     Instant messaging programs typically allow instant message senders to communicate in real-time with each other in a variety of ways. For example, many instant messaging programs allow instant message senders to send text as an instant message, to transfer files, and to communicate by voice. Examples of instant messaging communication applications include AIM 
     (America Online Instant Messenger), AOL (America Online) Buddy List and Instant Messages which is an aspect of many client communication applications provided by AOL, Yahoo Messenger, MSN Messenger, and ICQ, among others. Although discussed above primarily with respect to instant message applications, other implementations are contemplated for providing similar functionality in platforms and on-line applications. For example, the techniques and concepts may be applied to an animated avatar that acts as an information assistant to convey news, weather, and other information to a user of a computer system or a computing device. 
     The techniques and concepts generally have been described in the context of an instant messaging system that uses an instant messaging host system to facilitate the instant messaging communication between instant message senders and instant message recipients. Other instant message implementations are contemplated, such as an instant message service in which instant messages are exchanged directly between an instant message sender system and an instant message recipient system. 
     For example, although the examples above are given in an instant message context, other communications systems with similar attributes may be used. For example, multiple personalities may be used in a chat room or in e-mail communications. Also, the user interface may be a viewable interface, an audible interface, a tactile interface, or a combination of these. 
     The user interfaces are described as having windows for which a user may control the display position of each window on a display device. A user&#39;s control over the display position of a window may include, for example, indirect or direct control of the coordinates of the display device at which the window is positioned, the size of the window, and the shape of the window. Alternatively, any of the windows described herein may be implemented as a pane of a graphical user interface in which the pane is displayed in a fixed position on a display device. 
     The described systems, methods, and techniques may be implemented in digital electronic circuitry, computer hardware, firmware, software, or in combinations of these elements. Apparatus embodying these techniques may include appropriate input and output devices, a computer processor, and a computer program product tangibly embodied in a machine-readable storage device for execution by a programmable processor. A process embodying these techniques may be performed by a programmable processor executing a program of instructions to perform desired functions by operating on input data and generating appropriate output. The techniques may be implemented in one or more computer programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. Each computer program may be implemented in a high-level procedural or object-oriented programming language, or in assembly or machine language if desired; and in any case, the language may be a compiled or interpreted language. Suitable processors include, by way of example, both general and special purpose microprocessors. Generally, a processor will receive instructions and data from a read-only memory and/or a random access memory. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, such as Erasable Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and Compact Disc Read-Only Memory (CD-ROM). Any of the foregoing may be supplemented by, or incorporated in, specially-designed ASICs (application-specific integrated circuits). 
     It will be understood that various modifications may be made without departing from spirit and scope of the claims. For example, the steps of the disclosed techniques and concepts may be performed in a different order and/or the components in the disclosed systems may be combined in a different manner and/or replaced or supplemented by other components. As another example, a screen name is used throughout to represent a unique identifier of an account, but any other unique identifier of an account may be used to identify an account. Other implementations are within the scope of the following claims.