Communications system and related method for routing calls to a different destination

摘要

A communications session call is established between first and second call devices. A SIP Reinvite command is sent to the second call device without any SDP media parameters to gain new and current media parameters. The second call device acknowledges the Reinvite command as corresponding to the first SDP offer with new and current media parameters. A third call device is sent a SIP Reinvite command as a second SDP offer using new and current media parameters. The third call device acknowledges the SIP Reinvite command as corresponding to the first SDP answer to the first SDP offer. The second call device acknowledges as a second SDP answer to the second SDP offer. The call with the first call device is terminated to change the destination of the call and maintaining any media stream between the second and third call devices.

主权项

1. A method of routing a call comprising:
establishing, by a call control agent, a first Session Initiation Protocol (SIP) communications session call between a first communications endpoint and a second communications endpoint; sending, by the call control agent and to the second communications endpoint, a SIP Reinvite command that does not include Session Description Protocol (SDP) media parameters to gain current media parameters from the second communications endpoint, wherein the SIP Reinvite command is sent to the second device independent of the call control agent receiving the SIP Reinvite from another communications endpoint; receiving, by the call control agent and in response to the SIP Reinvite command, current media parameters of the first SIP communications session call from the second communications endpoint; sending, by the call control agent and to a third communications endpoint that is not included in the first SIP communications session call, an SDP offer that includes the current media parameters of the first SIP communications session call between the first communications endpoint and the second communications endpoint; receiving, by the call control agent and from the third communications endpoint, an SDP answer to the SDP offer; and in response to receiving the SDP answer from the third communications endpoint: establishing, by the call control agent, a second SIP communications session call between the second communications endpoint and the third communications endpoint based, at least in part, on the current media parameters of the first SIP communications session call between the first communications endpoint and the second communications endpoint; and terminating the first communications session call with the first communications endpoint while maintaining a media stream between the second communications endpoint and third communications endpoint.