SIP / ISDN Issue

[Pepp77]

Odd one.

Have a customer with a Gamma SIP trunk that works perfectly most of the time. Incoming isnt an issue, outgoing isnt an issue, incoming and then forwarded or twinned back out over the SIP is not an issue, Twinning out an incoming SIP call over ISDN not an issue, but forwarding an incoming SIP call out over ISDN results in the call being answered on the mobile but still ringing on the callers end.

SIP trunk programming and System VoIP tab programming are all good and match numerous other systems we have out there that do not experience this issue. System is on 9.0.12. This site we have no control over the firewall but customer uses a decent enough IT company who say nothing is amiss on the firewall and generally as SIP to SIP is fine I would agree with them.

Basically I am now asking if anyone has experienced the same issue and could advise the resolution they used.

| ACSS SME |

 

[wotanuta]

I have the exact same problem. SIP to SIP is fine but calls forwarded out from SIP to ISDN 30 is an issue. I am running 9.1.8 software.ANy advise would be much appreciated.

 

[janni78]

Do a Monitor trace, try to see if the it sends SIP OK when you get connect on the ISDN line.

Sounds like it could be a firmware issue.

"Trying is the first step to failure..." - Homer

 

[wotanuta]

I have this at 2 sites now, both 9.1.8 and the only thing they have in common is that they both use Drayteks 2860N routers. We have just set up a Gamma Leased line on one system and this works fine on SIP to ISDN calls. Not 100% sure it is the routers as they have said it worked when they had a V1 on 4.2. Puzzling but the isue does appear to be a media mismatch on the Sys Mon trace.

 

[amriddle01]

Drayteks can cause SIP issues for sure, we have swapped out/by passed many and the issues stop instantly