[Serusers] INVITE timeout

Greg Fausak greg at august.net
Sun Feb 8 15:56:07 CET 2004

I have an INVITE timeout problem.

My SIP layout includes:

              | EXTERNAL PSTN |
              | SIP SERVERS   |
              | MAIN INCOMING |
              | SIP SERVER    |
                |           |
                |           |
      +------------+      +-----------------+
      | SIP SERVER |      | SIP SERVER      |
      | DOMAINA.com|      | OtherDom.com    |
      +------------+      +-----------------+
          |                     |
          |                     |
      +----------+             +---------+
      | customerA|             |otherCust|
      +----------+             +---------+

I hope the ASCII drawing worked!

Calls come in from the top down.
The MAIN INCOMING server uses internal ENUM
to deliver the call to the correct domain
server.   Once delivered to that server,
if the customer does not answer his phone before
an INVITE timeout occurs the call is forwarded to

This works great when the call is from an external PSTN
server.  It also works great if a user in DOMAINA.com calls another
user in DOMAINA.com.

I am experiencing difficulty when a user in DOMAINA.com
calls a user in OtherDom.com.  The SER at DOMAINA.com
recognizes that INVITE is going to a foreign domain, and it
t_relays() the INVITE to the MAIN INCOMING SER.  It then gets
t_relayed() to OtherDom.com where the call is delivered.

The problem is both use the same INVITE timer, so the TIMEOUT
on DOMAINA.com occurs *before* the TIMEOUT on OtherDom.com, which
means that the call is not delivered to voicemail.

Any ideas?


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