Problems with incoming PSTN calls to VCS Control

[Stefan Wahl]

Hi everybody,

I´m testing the integration between CUCM and VCS and have a little problem regarding incoming PSTN calls.

The connections for inbound calls are:

PSTN gateway (3825) connected via H.323 to primary CUCM (7.0) which has a ICT to secondary CUCM (9.1) which has a SIP trunk to VCS Control.

For Outbound calls:

VCS via SIP trunk to secondary CUCM (9.1) which routes directly via H.323 to PSTN gateway.

Outgoing is working perfectly.

When I try to establish an incoming call I get the signalization on the C60 codec (P55D), but when I click on answer, the calls begins to ring again.

Anyone any idea, why this can happen?

Thanks in advance.

Stefan

[Martin Koch]

Any firewall, NAT, ALG, ... in the path? Any DNS issues?

Maybe thats a retransmitted INVITE as the 200 OK does not reach the CUCM.

Did you check for call loops?

Not sure regards the old version of CUCM and the SDP in the ok of the endpoint if that can also cause issues.

A sip trace and debugging session on the endpoint, vcs, cucm and gw might give you an answer.

RTMT and the call and search history + debug on the VCS can also be your friends.