Abstract:
A wireless terminal is dynamically placed into a call pickup group based on the location of the wireless telephone. Similarly, a wireless terminal is dynamically removed from a call pickup group on the basis of the location of the wireless terminal. A wireless terminal can be excluded from joining a call pickup group in a specific location.

Description:
TECHNICAL FIELD 
     This invention relates generally to wireless switching systems and, in particular, to telephone call management within such a system. 
     BACKGROUND OF THE INVENTION 
     When a number of telephones are situated in a common open area, a situation often arises where the user of one of the ringing telephones does not answer. It is highly desirable for another individual within the area to utilize their own telephone to answer the incoming call for the other telephone. Within the prior art this has been accomplished by placing the telephones within the common area into a call pickup group. If a first telephone within the call pickup group is being rung, a user of a second telephone of the call pickup group can actuate a designated button on their telephone or dial a special code to answer the call that is directed to the first telephone. 
     The prior art pickup groups have functioned well with wired telephone sets. Such pickup groups are manually administered on the telecommunication switching system providing service for the telephones within the pickup group. In particular, the prior art pickup groups and their administration have functioned well for the traditional business environment where an employee is assigned a desk or a specific location and performs their principle work function at that telephone or location. The traditional environment is slowly changing. In the emerging business environment, individuals do not have a wired telephone but rather they have a wireless telephone that they carry with them at all times and that is their only telephone. In addition, employees during the course of a day perform many functions at different locations. 
     SUMMARY OF THE INVENTION 
     The foregoing problems are solved, and a technical advance is achieved by an apparatus and method in which a wireless terminal is dynamically placed into a call pickup group based on the location of the wireless telephone. Similarly, a wireless terminal is dynamically removed from a call pickup group on the basis of the location of the wireless terminal. Advantageously, a wireless terminal can be excluded from joining a call pickup group in a specific location. 
     Other and further aspects of the present invention will become apparent during the course of the following description and by reference to the accompanying drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a block diagram of a wireless system for implementing the invention; 
     FIGS. 2,  3 , and  4  illustrate Table  1  that is maintained by a wireless switching system in implementing the invention; 
     FIGS. 5,  6 ,  7  and  13  illustrate, in flow chart form, steps performed by a wireless switching system; 
     FIG. 8 illustrates, in block diagram form, a fixed unit; 
     FIG. 9 illustrates, in block diagram form, a wireless terminal; 
     FIG. 10 illustrates, in flow chart form, steps performed by a wireless terminal; 
     FIG. 11 illustrates, in flow chart form, steps performed by a fixed unit; and 
     FIG. 12 illustrates Table  2  that is maintained by a wireless switching system. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 illustrates, in block diagram form, a wireless system for implementing the invention. Wireless switching system  101  via base stations  121 - 122  provides wireless service for wireless terminals  102 - 109  that are free to roam throughout cubicle areas  112 - 114 . Wireless switching system  101  constantly determines the location of each wireless terminal. This determination is performed in the following manner. Each fixed unit transmits at predefined intervals the identification of the fixed unit via a different transmission medium than utilized by the base stations  121 - 122 . This transmission medium may be an infrared transmission. Wireless terminals  102 - 109  have a receiver for receiving the infrared transmission from the fixed units. When a wireless terminal receives the identification code from a fixed unit, the wireless terminal establishes a data channel to wireless switching system  101  and transmits the identification of the fixed unit via this data channel. Wireless switching system  101  then records in Table  1  as illustrated in FIGS. 2,  3 , and  4  the identity of the fixed unit from which the wireless terminal is receiving an identification code. This information is placed into column  204  of Table  1 . 
     One skilled in the art could readily see that other methods could be utilized to determine the location of a wireless terminal. For example, the wireless terminals could transmit identification information defining the wireless terminal to a fixed unit which then could relay this information to wireless switching system  101  via wired or wireless media to wireless switching system  101 . In addition, global positioning satellite (GPS) devices or base stations could be used to determine a position of a wireless terminal. 
     In accordance with the invention, it is possible to establish a call pickup group based on the location of the wireless terminals. To understand this operation, consider the following example. A call pickup group is established for cubicle areas  113  and  114  but not for cubicle area  112 . In addition, as will be explained later in greater detail, it is possible for a wireless terminal to be marked in Table  1  indicating that when the wireless terminal enters a cubicle area having a call pickup group that the marked wireless terminal will not become part of this group. Table  1  illustrates that cubicle areas  113  and  114  have been set up as having call pickup groups by location as indicated in column  202 . Cubicle area  112  does not have a call pickup group established for it. Table  1  allows a wireless terminal to be marked as excluded from the call pickup groups of certain cubicle areas as indicated in column  203 . If a “0” is entered in column  203 , the wireless terminal is excluded from all areas. In the present example, wireless terminal  101  will not become part of the call pickup group for cubicle area  113  when wireless terminal  101  enters cubicle area  113  and receives transmission from fixed unit  115 . Similarly, wireless terminal  103  is excluded from the call pickup groups for both cubicle area  113  and  114 . 
     In operation, if a call is directed to wireless terminal  104  in cubicle area  113 , wireless switching system  101  searches Table  1  and determines that wireless terminals  105  and  106  are part of the call pickup group. Consequently, wireless switching system  101  transmits alerting (ringing) to wireless terminals  104 , but wireless terminals  105  and  106  can is pick the call up. The first of these wireless terminals to answer in response to the alerting signal will have the incoming call switched to it by wireless switching system  101 . If a call is directed to wireless terminal  102  in cubicle area  112 , only wireless terminal  102  is alerted, and wireless terminal  103  can not pick the call up since Table  1  of FIG. 2 in column  202  designates no call pickup group for cubicle area  112 . 
     Consider now when wireless terminals  102  and  103  leave cubicle area  112  and enter cubicle area  113 . Table  1  is updated as illustrated in FIG.  3 . Column  204  of Table  1  of FIG. 3 illustrates that wireless terminals  102  and  103  are now in communication with fixed unit  115 . When wireless terminal  102  entered cubicle area  113 , it became part of the call pickup group for cubicle area  113  as illustrated in column  202  of FIG. 3 since wireless terminal  102  is not marked as being excluded from being part of the call pickup group for cubicle area  113 . However, wireless terminal  103  did not become part of the call pickup group for cubicle area  113  since wireless terminal  103  is excluded from being part of a call pickup group in cubicle area  113  as marked in column  203  of FIG.  3 . If a call comes in once again for wireless terminal  104 , wireless switching system  101  searches column  202  and determines that wireless terminals  102 , and  104 - 106  are part of a call pickup group for cubicle area  113  of which wireless terminal  106  is located. Based on this determination, wireless switching system  101  alerts wireless terminal  104 , and wireless terminals  102 ,  105  and  106  can pick the call up. 
     As illustrated in FIG. 12, each cubicle area is assigned a unique telephone number. When an incoming call is received, wireless switching system  101  examines Table  2  of FIG.  12 . If an entry is found for the called telephone number, wireless switching system  101  then examines Table  1  of FIGS. 2-4 to determine which wireless terminals are part of a call pickup group for that cubicle area. For example, if an incoming call is received for telephone number 538-2903, wireless switching system  101  examines Table  2  and determines that this is the area telephone number for cubicle area  113 . Wireless switching system  101  then examines to Table  1 . Examining Table  1  of FIG. 2, wireless switching system  101  would find that wireless terminals  104 - 106  are the call pickup group for location  113 . Wireless switching system  101  then alerts wireless terminal  104  since it is the first wireless terminal in column  201  associated with location  114 . Wireless terminals  105  and  106  can answer the call. One skilled in the art could readily envision other algorithms could be used to select the wireless terminal to be alerted out of the call pickup group. 
     FIG. 4 reflects the changes to Table  1  when wireless terminal  103  moves back into cubicle area  112 , and wireless terminal  107  moves into cubicle area  113 . The call pickup group for cubicle area  113  comprises wireless terminals  102  and  104 - 107 . The call pickup group for cubicle area  114  is made up of only wireless terminals  108  and  109 . 
     FIGS. 5,  6  and  7  illustrate, in flow chart form, the steps performed by wireless switching system  101  in implementing the invention. Decision block  501  determines if a message has been received from a wireless terminal. If the answer is no in decision block  501 , control is transferred to decision block  502  which determines if an incoming call is being received for one of the wireless terminals. If the answer is no, control is transferred to decision block  1301  of FIG.  13 . If the answer in decision block  502  is yes, control is transferred to decision block  701  of FIG.  7 . 
     If the answer in decision block  501  is yes, decision block  507  determines if a “no fixed unit” message is being received from a wireless telephone. Such a message indicates that a wireless telephone is not receiving the transmission signal from any fixed unit. If the answer is yes in decision block  507 , control is transferred to block  504  which determines the last known location. Wireless switching system  101  maintains a list of last known locations for each of the wireless terminals. Block  506  then signals that the wireless telephone cannot receive a fixed unit around the last location listed for the wireless telephone. This signaling may be in the form of a message displayed to an operator of wireless switching system  101  or merely a message being included in a maintenance log of wireless switching system  101 . After execution of block  506 , control is transferred back to decision block  501 . 
     Returning to decision block  507 , if the answer is no, decision block  508  determines if a low battery indication was included in the message identifying the fixed unit from the wireless telephone. If the answer is no in decision block  508 , block  509  determines the location based on the identification code of the fixed unit of the wireless telephone before transferring control to decision block  601  of FIG.  6 . If the answer in decision block  508  is yes, the low battery indication for the identified fixed unit is placed in the database by block  511 , and a maintenance message indicating low battery is generated before transferring control to block  512 . Block  512  performs the same operations as block  509  before transferring control to decision block  601  of FIG.  6 . 
     After the determination of the location of a wireless terminal has been made in either block  509  or  512 , control is transferred to decision block  601  of FIG.  6 . The latter decision block determines if the location of the wireless terminal has changed by examining column  204  of Table  1 . If the answer is no, control is transferred back to decision block  501  of FIG.  5 . If the answer in decision block  601  is yes, control is transferred to decision block  602  which determines if the wireless terminal is excluded from entering a call pickup group of the new location by examining column  203  of Table  1  of FIGS. 2-4. If the answer is yes in decision block  602 , control is transferred to block  605  whose operations will be described later. If the answer in decision block  602  is no, decision block  603  determines if there is a call pickup group for the new location. If the answer is no, control is transferred to block  605 . If the answer is yes in decision block  603  that there is a call pickup group for the new location, block  604  adds the wireless terminal into the call pickup group for the new location by updating column  202  of Table  1  of FIGS. 2-4 before transferring control to block  605 . The latter block updates column  204  of table  1  to reflect the fixed unit from which the wireless terminal is now receiving identification information. Then, decision block  606  determines if the wireless terminal was in a call pickup group for the previous location by examining column  202  of Table  1  of FIGS. 2-4. If the answer is no, control is transferred back to decision block  501  of FIG.  5 . If the answer is yes in decision block  606 , block  607  removes the wireless terminal from the previous call pickup group by administering column  202  of Table  1  of FIGS. 2-4 before transferring control back to decision block  501  of FIG.  5 . 
     Returning to decision block  502 , if the answer is yes, control is transferred to decision block  700  of FIG.  7 . The latter block determines if the called number is for an cubicle area by examining Table  12 . If the answer is yes in decision block  700 , control is transferred to block  705  which determines the call pickup group for the cubicle area by examining Table  1  of FIGS. 1-4 before transferring control to block  702 . If the answer in decision block  700  is no, control is transferred to decision block  701 . The latter decision block determines if the called wireless terminal is part of a call pickup group by examining columns  201  and  202  of Table  1  of FIGS. 2-4. If the answer is yes, all of the wireless terminals that are part of the call pickup group are determined by block  702 , and block  703  alerts the called wireless terminal and initializes for allowing the other wireless terminals that are part of the call pickup group to pickup the call before transferring control back to decision block  501  of FIG.  5 . If the answer in decision block  701  is no, block  704  only alerts the called wireless terminal before transferring control back to decision block  501  of FIG.  5 . 
     Returning again to decision block  502  of FIG. 5, if the answer is no, control is transferred to decision block  1301  of FIG.  13 . The latter block determines if a call origination has occurred in a wireless terminal. If the answer is no, control is transferred to decision block  1302  to determine if a pickup button has been actuated on a wireless terminal. The actuation of a pickup button indicates that the wireless terminal wishes to pickup a ringing call. If the answer is no in decision block  1302 , control is transferred to block  1303  for normal processing before control is returned back to decision block  501  of FIG.  5 . If the answer in decision block  1302  is yes indicating that a pickup button has been actuated, control is transferred to decision block  1306 . Returning to decision block  1301 , if a call origination has occurred, decision block  1304  determines if the wireless terminal is dialing a pickup access code. If the answer is no, control is transferred to block  1303  whose operations were previously described. If a pickup access code is being dialed, control is transferred to decision block  1306  that determines if pickup is allowed for this wireless terminal. If the answer is no, the wireless terminal receives intercept tone by execution of block  1307  before control is returned back to decision block  501  of FIG.  5 . If the answer in decision block  1306  is yes, decision block  1308  determines if there is a call pending for the pickup group of which the wireless terminal is part. If the answer is no, control is transferred to block  1307  whose operations were previously described. If the answer in decision block  1308  is yes, block  1309  connects the incoming call to the wireless terminal before transferring control back to decision block  501  of FIG.  5 . 
     FIG. 8 illustrates in block diagram form a fixed unit. The fixed unit of FIG. 8 is powered by battery  801 . However, one skilled in the art could readily see that normal building AC power could also be utilized to power the fixed unit. Controller  803  periodically transmits the identification code for the fixed unit via transmitter  804 . Advantageously, transmitter  804  can be transmitting utilizing infrared transmission or ultrasonic transmission. Transmitters for transmitting either infrared or ultrasonic are well known in the art. If controller  803  detects that battery  801  is at a low power level via conductor  807 , battery monitor  802 , and conductor  808 , controller  803  sets alarm indicator  805  and transmits the low power indication along with the identification code via transmitter  804 . 
     Wireless handset  112  is illustrated in greater detail in FIG.  9 . Wireless handset  112  implements a wireless protocol that allows wireless handset  112  to maintain a wireless signal link with wireless switching system  101  via base stations  121 - 122 . One air interface that can be used is the Japanese PHS protocol as set forth in “User-Network Interface and Inter-Network Interface Standards for PHS”, the Telecommunication Technology Committee, 1995, and “Personal Handy Phone System RCR Standard”, Version 1, RCR STD-28, Dec. 20, 1993. The message set of the PHS protocol is similar to the ISDN message set. Overall control of the wireless handset is provided by control unit  901 . Units  902 ,  903 ,  906 ,  907 ,  908 , and  909  provide the RF communication capabilities for the wireless handset. Elements  904 ,  910 , and  911 - 914  provide the audio information received and transmitted to the user; whereas, elements  916 - 918  and  905  provide the basic user interface. The PHS protocol allows control unit  901  to establish a logical data channel with wireless switching system  101 . Control unit  901  utilizes this logical data channel to transmit identification information for fixed units to wireless switching system  101 . Fixed unit receiver  921  receives the identification code of a fixed unit and transfers this identification code to control unit  901  for transmission to wireless switching system  101 . Fixed unit receiver  921  is of a design well known in the art for either infrared or ultrasonic transmission media. One skilled in the art could readily see that fixed unit receiver  921  could provide to control unit  901  the signal strength of the received signal. Further, control unit  901  could also tune fixed unit receiver  921  to receive different frequencies or other variations of the transmission media using well known techniques in the art. 
     FIG. 10 illustrates the steps performed by a wireless terminal such as wireless handset  113 . Decision block  1001  determines if the time has elapsed to monitor for a fixed unit. Advantageously, every second the wireless handset monitors to determine if the transmission signal of a fixed unit is being received. If the answer in decision block  1001  is no, normal processing is performed by block  1002  before control is returned back to decision block  1001 . 
     If the answer in decision block  1001  is yes, control is transferred to decision block  1003  which determines if a transmission signal is being detected. If the answer in decision block  1003  is no, control is transferred to block  1004  which establishes a logical channel to wireless switching system  101  via a base station. After the establishment of the logical channel, the wireless handset transmits a “no fixed unit” message to the central computer in block  1006  before transferring control back to decision block  1001 . Returning to decision block  1003 , if the answer is yes, control is transferred to block  1008  which establishes a logical channel to wireless switching system  101 . Block  1009  determines the identification code of the fixed unit whose transmission signal is being received, and block  1011  transmits the received identification code to wireless switching system  101  before transferring control to decision block  1012 . Decision block  1012  determines if a low battery indication was included in the transmission signal from the fixed unit. If the answer is no, control is transferred back to decision block  1001 . If the answer in decision block  1012  is yes, block  1013  transmits a low battery indication message to wireless switching system  101  for the identified fixed unit and also returns control to  1001 . FIG. 11 illustrates the steps performed by a fixed unit. Decision block  1101  determines if it is time to transmit the identification code of the fixed unit. Advantageously, the identification code is transmitted every tenth of a second. If the answer is no, control is transferred back to decision block  1101 . If the answer is yes, decision block  1103  determines if battery monitor  802  of FIG. 8 is indicating a low battery. If the answer is no, block  1104  simply transmits the identification code of the fixed unit before transferring control back to decision block  1101 . If the answer in decision block  1103  is yes, block  1106  transmits a message that includes the identification code and a low battery indication before transferring control back to decision block  1101 . 
     Of course, various changes in modification to the illustrated embodiment described above will be apparent to those skilled in the art. These changes and modifications can be made without departing from the spirit and scope of the invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the following claims.