[Sip-implementors] PSTN - SIP Interworking

[Jagannathan R]

PSTN to SIP interworking, the main purpose of this development work is to allow any PSTN subscriber to call SIP user and vice versa. The interconnection between SIP and PSTN is being worked out as User Agent Function in MGC(softswitch). This User Agent Function will work as UAC for PSTN-SIP calls and UAS for SIP-PSTN calls. And this User Agent will have connectivity with Proxy Server, who will distribute the calls both ways. I have few gray points, can any one clarify please   1. When Proxy server boots up, how will it inform to User Agent about its availability or the status.     In case of the non-availability/out of service of this Proxy, can we have some sort of backup Proxy. 2. How this primary and backup Proxies be configured to the User Agent. 3. When simultaneous calls are being processed between them both ways,     what method can be adopted to sequences these calls. 4. Is there any thing like call capacity in this part of link i.e. between User Agent and Proxy required? 5. When SIP user dials a PSTN number, how location server/Proxy server route this call to PSTN network.     Should All / range of PSTN numbers register with Proxy?     And for registering can we have IP address as a host name?   Thanks in Advance,   jagannathan