EE 284 Lecture Notes - Lecture 12: Public Switched Telephone Network, Infor, Circuit Switching
Document Summary
The invite method can also be used for establishing a multiparty call. Once it has received a final response to an invite, the client that initi- ated the invite sends an ack. Ack method is used as a confirmation that the final response has been received. For example, if the response to an invite indicates that the called user is busy and the call cannot be com- pleted at that time, then the calling client will send an ack. On the other hand, if the response to the invite indicates that the called user is being alerted or that the call is being forwarded, then the client does not send ack, because such responses are not considered final. The method can be issued by either the calling or called party and is used when the party in question hangs up. The options method queries a server as to its capabilities.
