[Generic SIP Trunk] Connect 2 trunks from the same provider

[FS_Mathieu]

Hello everyone, it's been a while !

I'm testing 3CX with our homemade french provider Netiwan. I'm facing an issue :

When I connect 2 trunks on the same SBC (same host but differents IDs) it seems like 3CX is only reognizing one of them.

In the logs of my SBC I see that the call goes to the trunk #2 but in 3CX it is routed to the default user of the trunk #1.

Is there a way to differentiate them with customizing the domain of the source or something like that ?

Best regards,
Mathieu

 

[SteveITS]

I had what might be a similar issue with a US provider once, trying to work around a caller ID problem. We found they could not tell the difference between the first and second connection, they said because the call was coming from the same IP and port on our 3CX server. Our workaround was to have our trunk 2 connect to their backup server hostname. Not ideal but it worked until they fixed the outbound caller ID problem.

 

[FS_Mathieu]

Hello,

That's the case I'm actually facing, I'm connecting both trunks on the same IP but only one is registering.

What's the point between Caller ID and Registering ? How did you unlock that ?

Best regards,
Mathieu

 

[SteveITS]

In our specific case, the workaround was to have the second trunk connect to the SIP provider's backup server. So:

trunk 1: connect to sip.example.com
trunk 2: connect to backupsip.example.com

Eventually the SIP provider updated their process to allow us to send the outbound caller ID with the call, so we no longer needed the second trunk.

 

[FS_Mathieu]

Yeah I got it, I will check and try if we can provide a second registrar address to avoid this kind of problem.

But that's only dodging the problem, 3CX should be able to register 2 trunks from the same registrar

 

[SteveITS]

3CX should be able to register 2 trunks from the same registrar

In our case it was a limitation/bug of the SIP provider. I was told by their support that if the server was behind NAT it would have used different source ports and thus been detected as the second connection, but without NAT when the same source port was used they couldn't tell the difference. I skimmed the ticket and found this tidbit which may be relevant:
“with this provider there is no concept of ‘connection’ because” [the SIP provider]’s SRV records are using UDP not TCP.

However I just reread your original message. As I recall, in our case 3CX logs did show the call going out the second trunk according to the outbound rule but the SIP provider was assuming it was the first trunk.