Seamless Call Switching In A Dual Mode Environment

Abstract

Methods and apparatus for providing a seamless switching of voice calls between different wireless networks are disclosed. In one illustrative example, a mobile communication device has a processor and one or more wireless transceivers coupled to the processor. The one or more wireless transceivers include a first transceiver portion operative in accordance with a first wireless network (e.g. a GSM/GPRS cellular network) and a second transceiver portion operative in accordance with a second wireless network (e.g. an 802.11 wireless network). A voice call is maintained between the mobile device and a communication terminal through call control equipment. The processor of the mobile device is operative to maintain voice communications for the voice call over a traffic channel established between the mobile device and the first wireless network using the first transceiver portion; cause a connecting call to be established with the communication terminal through the call control equipment in response to a predetermined condition, where the connecting call involves a traffic channel established between the second wireless network and the mobile device using the second transceiver portion; and after the connecting call is established, maintain voice communications for the voice call over the traffic channel established between the second wireless network and the mobile device.

1 . A method for use by a mobile communication device in switching a voice call between two different wireless communication networks, the method comprising the steps of:
 maintaining voice communications for a voice call with a communication terminal through call control equipment, the voice call involving a traffic channel established between a first wireless network and the mobile device with use of a first transceiver portion which operates in accordance with the first wireless network;   causing a connecting call to be established with the communication terminal through the call control equipment based on identifying a predetermined condition, the connecting call involving a traffic channel established between a second wireless network and the mobile device using a second transceiver portion which operates in accordance with the second wireless network; and   after the connecting call is established, maintaining voice communications for the voice call over the traffic channel established between the second wireless network and the mobile device.   
     
     
         2 . The method of  claim 1 , wherein one of the first and the second wireless networks is operative in accordance with a cellular telecommunications network and the other one of the first and the second wireless networks is operative in accordance with an 802.11 based wireless network. 
     
     
         3 . The method of  claim 1 , wherein the first wireless network is operative in accordance with a first cellular telecommunications network and the second wireless network is operative in accordance with a second cellular telecommunications network different from the first cellular telecommunications network. 
     
     
         4 . The method of  claim 1 , wherein the step of causing the connecting call to be established further comprises:
 receiving a call initiation message from the second wireless network for the connecting call; and   causing a call answering message to be sent to the second wireless network based on receiving the call initiation message from the second wireless network, for thereby establishing the traffic channel between the second wireless network and the mobile device.   
     
     
         5 . The method of  claim 1 , wherein the step of causing the connecting call to be established further comprises:
 causing a network switching message to be sent to the call control equipment;   receiving a call initiation message from the second wireless network for the connecting call in response to sending the network switching message to the call control equipment; and   causing a call answering message to be sent to the second wireless network based on receiving the call initiation message from the second wireless network, for thereby establishing the traffic channel between the second wireless network and the mobile device.   
     
     
         6 . The method of  claim 1 , wherein the predetermined condition comprises one of a poor signal condition with the first wireless network, a predetermined signal detection from the second wireless network, and a user input signal at the mobile device. 
     
     
         7 . The method of  claim 1 , wherein the step of causing the connecting call to be established further comprises:
 initiating the connecting call to the call control equipment by sending a call initiation message to the second wireless network.   
     
     
         8 . The method of  claim 1 , further comprising:
 causing the traffic channel with the first wireless network to be terminated after maintaining the voice communications with the second wireless network.   
     
     
         9 . The method of  claim 1 , wherein the connecting call comprises a conference call type connection with the voice call through the call control equipment. 
     
     
         10 . A mobile communication device, comprising:
 one or more processors;   one or more wireless transceiver coupled to the one or more processors;   the one or more wireless transceivers having a first transceiver portion operative in accordance with a first wireless network and a second transceiver portion operative in accordance with a second wireless network;   the one or more processors being operative to:
 maintain voice communications for a voice call with a communication terminal through call control equipment, the voice call involving a traffic channel established between the first wireless network and the mobile device with use of the first transceiver portion; 
 cause a connecting call to be established with the communication terminal through the call control equipment based on identifying a predetermined condition, the connecting call involving a traffic channel established between the second wireless network and the mobile device with use of the second transceiver portion; and 
 after the connecting call is established, maintain voice communications for the voice call over the traffic channel established between the second wireless network and the mobile device. 
   
     
     
         11 . The mobile device of  claim 10 , wherein one of the first and the second wireless networks is operative in accordance with a cellular telecommunications network and the other one of the first and the second wireless networks is operative in accordance with an 802.11 based wireless network. 
     
     
         12 . The mobile device of  claim 10 , wherein the first wireless network is operative in accordance with a first cellular telecommunications network and the second wireless network is operative in accordance with a second cellular telecommunications network different from the first cellular telecommunications network. 
     
     
         13 . The mobile device of  claim 10 , wherein the one or more processors are further operative to cause the connecting call to be established by:
 receiving a call initiation message from the second wireless network for the connecting call; and   causing a call answering message to be sent to the second wireless network based on receiving the call initiation message from the second wireless network, for thereby establishing the traffic channel between the second wireless network and the mobile device.   
     
     
         14 . The mobile device of  claim 10 , wherein the one or more processors are further operative to cause the connecting call to be established by:
 causing a network switching message to be sent to the call control equipment;   receiving a call initiation message from the second wireless network for the connecting call in response to sending the network switching message to the call control equipment; and   causing a call answering message to be sent to the second wireless network based on receiving the call initiation message from the second wireless network, for thereby establishing the traffic channel between the second wireless network and the mobile device.   
     
     
         15 . The mobile device of  claim 10 , wherein the predetermined condition comprises one of a poor signal condition with the first wireless network, a predetermined signal detection from the second wireless network, and a user input signal at the mobile device. 
     
     
         16 . The mobile device of  claim 10 , wherein the one or more processors are further operative to cause the connecting call to be established by:
 initiating the connecting call to the call control equipment by sending a call initiation message to the second wireless network.   
     
     
         17 . The mobile device of  claim 10 , wherein the one or more processors are further operative to cause the connecting call to be established by:
 causing the traffic channel with the first wireless network to be terminated after maintaining the voice communications with the second wireless network.   
     
     
         18 . The mobile device of  claim 10 , wherein the voice communications of the voice call comprises Voice over IP (VoIP) communication through one of the first and the second wireless networks.