Abstract:
A method for facilitating a call session includes receiving a request to establish a call session between a wireless phone and a remote phone, and establishing a call session between the wireless phone and the remote phone. The call session includes a first connection with the wireless phone and a second connection with the remote phone. The method further includes monitoring the first connection to determine if there is a connection loss of the first connection, and determining that there is a connection loss of the first connection. In response to determining that there is a connection loss of the first connection, the method further includes holding the second connection with the remote phone, attempting to reestablish the first connection with the wireless phone, and resuming the call session in response to the first connection being reestablished.

Description:
TECHNICAL FIELD 
     This invention relates in general to facilitating a call session between a wireless phone and a remote phone, and more particularly to avoiding call drop for the call session. 
     BACKGROUND 
     Traditionally, when a user is using a wireless phone to participate in a phone call session with a remote peer phone, the radio signal associated with the wireless phone can sometimes be lost due to radio interference or movement of the user. As a result, the signaling and payload communication between the wireless phone and the remote peer phone is lost, resulting in the phone call session being dropped. In order to reestablish the call session, a user is required to redial the phone number of the other phone. 
     SUMMARY 
     In accordance with one embodiment of the present invention, there is provided a method for facilitating a call session including receiving a request to establish a call session between a wireless phone and a remote phone, and establishing a call session between the wireless phone and the remote phone. The call session includes a first connection with the wireless phone and a second connection with the remote phone. The method further includes monitoring the first connection to determine if there is a connection loss of the first connection, and determining that there is a connection loss of the first connection. In response to determining that there is a connection loss of the first connection, the method further includes holding the second connection with the remote phone, attempting to reestablish the first connection with the wireless phone, and resuming the call session in response to the first connection being reestablished. 
     In accordance with another embodiment of the present invention, a system for facilitating a call session includes a wireless phone, a remote phone, and a call relay station. The call relay station is adapted to receive a request to establish a call session between the wireless phone and the remote phone, and establish a call session between the wireless phone and the remote phone. The call session includes a first connection with the wireless phone and a second connection with the remote phone. The call relay station is further adapted to monitor the first connection to determine if there is a connection loss of the first connection, and determine that there is a connection loss of the first connection. In response to determining that there is a connection loss of the first connection, the call relay station is further adapted to hold the second connection with the remote phone, attempt to reestablish the first connection with the wireless phone, and resume the call session in response to the first connection being reestablished. 
     An advantage of certain embodiments of the present invention is that call drop due to temporary loss of a radio signal when using a wireless phone can be avoided. 
     Other technical advantages of the present invention will be readily apparent to one skilled in the art from the following figures, descriptions, and claims. Moreover, while specific advantages have been enumerated above, various embodiments may include all, some, or none of the enumerated advantages. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention and its advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a block diagram of a system for avoiding call drop in accordance with an embodiment of the present invention; 
         FIG. 2  is a flow diagram of a process for avoiding call drop using a call relay station in accordance with an embodiment of the present invention; 
         FIG. 3  is a signaling diagram of a process for avoiding call drop in accordance with an embodiment of the present invention; and 
         FIG. 4  is a block diagram of another system for avoiding call drop in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In accordance with some embodiments of the invention, a wireless phone, such as, for example, a wireless (802.11) Internet Protocol (IP) phone or mobile phone, is assigned to a call relay station, preferably in geographic proximity to the wireless phone, to avoid call drop due to temporary loss of the radio signal associated with the wireless phone. The system finds a reliable call relay station to which to assign the wireless phone. During a call session between the wireless phone and a remote peer phone, the call relay station continuously monitors the connection to the wireless phone, holds or parks the call session if the connection to the wireless phone is dropped due to loss of the radio signal, and resumes the call session when the connection is re-established. This allows a call session to be reestablished without requiring a user to redial the phone number associated with the other phone in the call session. 
       FIG. 1  is a block diagram of a system  100  for avoiding call drop in accordance with an embodiment of the present invention. The system  100  includes a wireless phone  105  having a wireless connection to a call relay station  110 . The wireless phone  105  is assigned to the call relay station  110  during call setup. In at least one embodiment, wireless phone  105  may include a wireless Internet Protocol (IP) phone or a mobile phone. In at least one embodiment of the invention, the call relay station  110  is located in geographical proximity to the wireless phone  105 . In some embodiments of the invention, the call relay station  110  can be a router or gateway. 
     The system  100  further includes a remote peer phone  115  coupled to the call relay station  110 . In accordance with various embodiments of the invention, the remote peer phone  115  is coupled to the call relay station  110  through a reliable connection such as a wireline or mostly wireline connection. Accordingly, communication between the call relay station  110  and the remote peer phone  115  is not affected by the radio signal to the wireless phone  105 . In accordance with one embodiment, the connection of the remote peer phone  115  to the call relay station  110  is through a public switched telephone network (PSTN) and/or packet switched network. 
     In some embodiments, a request to establish a call session between the remote peer phone  115  and the wireless phone  105  is sent by the remote peer phone  115  to the call relay station  110 . In at least one embodiment, the request is initiated by a user of the remote peer phone  115  dialing a telephone number associated with the wireless phone  105 . In response to the request to establish the call session, the call relay station  110  establishes a first call connection to the remote peer phone  115  and a second call connection to the wireless phone  105 . During the call session, the call relay station  110  relays voice or other payload data between the wireless phone  105  and the remote peer phone  115 . 
     During the call session, the call relay station  110  continuously monitors the connection to the wireless phone  105 . If the connection is lost due to the loss of the radio signal, the call relay station  110  holds or parks the call so that the connection to the remote peer phone  115  is still active. In at least one embodiment, the call relay station  110  sends an announcement message to the remote peer phone  115  to initiate playing of the announcement message by the remote peer phone  115  to the user of the remote peer phone  115  to ask the user to hold the phone until the connection between the wireless phone  105  and the call relay station  120  is automatically reestablished. In addition, the wireless phone  105  may continuously play an announcement message to a user of the wireless phone  105  to hold and not hang up while the call relay station  110  attempts to reestablish the call connection with the wireless phone  105 . 
     After the connection is lost, the call relay station attempts to reestablish the call connection with the wireless phone  105 . The call relay station further includes a timer that is started when holding or parking the connection with the remote peer phone  115  upon loss of the connection to the wireless phone  105 . If after a predetermined time the connection to the wireless phone  105  has not been reestablished or the remote peer phone  115  hangs up, the call session is disconnected. When the timer expires before the connection to the wireless phone  105  can be reestablished, the call relay station  110 , may play an announcement message to notify the remote peer that the call session has been disconnected. 
     If the connection to the wireless phone  105  is reestablished before the timer expires, the call relay station  110  stops playing the announcement message to the remote peer phone  115  and restore relaying the payload between the wireless phone  105  and the remote peer phone  115 . At the same time, the wireless phone  105  also stops playing the hold announcement message to its user and restores the payload between itself and the call relay station  110 . As a result, the call session is reestablished between the wireless phone  105  and the remote peer phone  115 . 
     Although the foregoing embodiment describes a situation in the remote peer phone  115  initiates a call to the wireless phone  105 , it should be understood that in other embodiments, a call can be initiated by the wireless phone  105 . 
     In at least one embodiment, the user can selectively enable the assigning of the wireless phone  105  to the call relay station  110  to avoid call drop for an important incoming or outgoing call, and disable the assigning of the wireless phone  105  to the call relay station  110  for less important calls. In addition, in at least one embodiment, the user can choose to enable or disable the assigning of the wireless phone  105  to the call relay station  110  either before or after a call is connected. Accordingly, the user can have a choice to always assign the wireless phone  105  to the call relay station  110  for all incoming or outgoing calls, or the user can activate this feature on a call by call basis dependent upon his or her choice before or after the call is connected. 
       FIG. 2  is a flow diagram of a process  200  for avoiding call drop using a call relay station in accordance with an embodiment of the present invention. The process begins at a step  205 . In a step  210 , the call relay station  110  receives a call setup request from the remote peer phone  115 . In step  215 , the call relay station  110  sends a call connection message to the wireless phone  215 . In step  220 , a determination is made regarding whether a connection between the call relay station  110  and the wireless phone  105  has been established. 
     If it is determined in step  220  that the connection between the call relay station  110  and the wireless phone  105  has not been established, the call relay station  110  sends a busy signal to remote peer phone  115  in a step  225 . After step  225 , the call session is ended in a step  280 , and the process is stopped in a step  285 . 
     If it is determined in step  220  that the connection between the call relay station  110  and the wireless phone  105  has been established, the call relay station sends a call connect message to remote peer phone  115  in step  230 . In step  235 , a call session is established between the wireless phone  105  and the remote peer phone  115 . During the call session, the payload of the call session is relayed between the wireless phone  105  and the remote peer phone  115  by the call relay station  110 . 
     During the call session, the call relay station  110  monitors the connection with the wireless phone in a step  240 . In a step  245 , a determination is made in step  245  regarding whether there has been a hang up of the call by either the wireless phone  105  or the remote peer phone  115 . If it has been determined in step  245  that the call has been hung up, the process continues to step  280  in which the call session is ended. If it is determined in step  245  that the call has not been hung up, a determination is made in a step  250  regarding whether call payload has been lost between the wireless phone  105  and the call relay station  110 . Call payload loss between the wireless phone  105  and the call relay station  110  is indicative of connection loss between the wireless phone  105  and the call relay station  110  due to loss of the radio signal between the wireless phone  105  and the call relay station  110 . 
     If it is determined in step  250  that call payload has not been lost, the process returns to step  240  in which the connection between the call relay station  110  and the wireless phone  105  is monitored. 
     If it is determined in step  250  that call payload has been lost, the call relay station  110  assumes that the connection between the call relay station  110  and the wireless phone  105  has been lost, and the call relay station  110  holds the connection with the remote peer phone  115  in step  255 . 
     In step  260 , the call relay station  110  attempts to reestablish the connection with the wireless phone  105 . In step  265 , the call relay station  110  makes a determination regarding whether the connection with the wireless phone  105  has been established. If it is determined in step  265  that the connection has not been reestablished, the call relay station  110  determines if a timer indicative of a predetermined maximum allowable time for reestablished of the connection has expired in a step  270 . If it is determined in step  270  that the timer has not expired, the process returns to step  260  is which the call relay station  110  continues to attempt to reestablish the connection with the wireless phone  105 . If it is determined in step  270 , that the timer has expired, the process continues to step  280  in which the call session is ended. 
     If it is determined in step  265  that the connection has been reestablished, the call session resumes in step  275 . After reestablishment of the call session, the relaying of the payload of the call session between the wireless phone  105  and the remote peer phone  115  is resumed by the call relay station  110 . After resuming the call session in step  275 , the process returns to step  240  in which the call relay station  110  monitors the connection between the call relay station  110  and the wireless phone  105 . 
     In various embodiments of the invention, software embodied in a computer readable medium can comprise computer code such that when executed is operable to perform the steps described with respect to  FIG. 2 . 
       FIG. 3  is a signaling diagram of a process  300  for avoiding call drop in accordance with an embodiment of the present invention. In the process  300 , the remote peer phone  115  sends a call setup request  305  to the call relay station  110 . The call setup request  305  includes a request to establish a call session with the wireless phone  105 . After receiving the call setup request  305  from the remote peer phone  115 , the call relay station establishes a connection  310  with the wireless phone  105 . After establishing the connection  310  with the wireless phone  105 , the call relay station establishes a connection  315  with the remote peer phone  115 . 
     After establishing the connection  315  with the remote peer phone  115 , the call relay station  110  establishes a call session  320  between the remote peer phone  115  and the wireless phone  105  in which payload between the remote peer phone  115  and the wireless phone  105  is relayed by the call relay station  110 . 
     In the embodiment illustrated in  FIG. 3 , the call between the call relay station  110  and the wireless phone  105  is dropped such as from loss of the radio signal between the call relay station  110  and the wireless phone  105 . The call relay station  110  then sends a message  330  to the remote peer phone  115  to keep the connection alive between the remote peer phone  115  and the call relay station  110 . The call relay station  110  then reestablishes connection  335  with the wireless phone  105 , and the call session is resumed in step  340 . 
       FIG. 4  is a block diagram of another system  400  for avoiding call drop in accordance with an embodiment of the present invention. The system  400  includes a wireless phone  105 , a remote peer phone  115  and a first call relay station  110   a  and a second call relay station  110   b . In accordance with the embodiment illustrated in  FIG. 4 , the wireless phone  105  can be associated with either the first call relay station  110   a  or the second call relay station  110   b . The call relay station  110   a  and the call relay station  110   b  operate in a similar manner to the call relay station  110  described with respect to  FIGS. 1-3  except that the first call relay station  110   a  and the second call relay station  110   b  support roaming of the wireless phone  105 . In the system  400  of  FIG. 4 , handoff of a call connection with wireless phone  105  between the first call relay station  110   a  and the second call station  110   b  is allowed. 
     For example, when a call is first established between the remote peer phone  115  and the wireless phone  105 , and the wireless phone  105  is in a geographical area serviced by the first call relay station  110   a , the wireless phone  105  is assigned to the first call relay station  110   a . Payload information associated with the call session between the wireless phone  105  and the remote peer phone  115  is relayed by the first call relay station  110   a . If the connection between the wireless phone  105  and the first call relay station  110   a  is lost, the first call relay station  110   a  attempts to reestablish the connection in the same or similar manner as the call relay station  110  described with respect to  FIGS. 1-3 . 
     If the wireless phone  105  moves out of the geographical area serviced by the first call relay station  110   a , to the geographical area serviced by the second call relay station  110   b , the connection with the wireless phone  105  is handed-off from the first call relay station  110   a  to the second call relay station  110   b . Payload information associated with the call session between the wireless phone  105  and the remote peer phone  115  is then relayed by the second call relay station  110   b . If the connection between the wireless phone  105  and the second call relay station  110   b  is lost, the second call relay station  110   b  attempts to reestablish the connection in the same or similar manner as the call relay station  110  described with respect to  FIGS. 1-3 . 
     An example application of the principles of the present invention may be for use in a supermarket, department store, or wholesaler using wireless (802.11) IP phones or customer service. When a store clerk walks around using a wireless (802.11) IP phone, the clerk may encounter loss of the radio signal. In accordance with certain embodiments of the invention, the call is put on hold when the signal loss is encountered, and automatically restored when the clerk moves to a place in which the radio signal is recovered. The call relay station can be located at the store close to all of the wireless (802.11) IP phone used in the store. 
     Although the present invention has been described with several embodiments, a myriad of changes, variations, alterations, transformations, and modifications may be suggested to one skilled in the art, and it is intended that the present invention encompass such changes, variations, alterations, transformations, and modifications as fall within the scope of the appended claims.