Using 3CX as Outbound Gateway for a Third-Party PBX, need help with Call Routing

Jaapy

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Hi everyone,

I'm currently working on a setup where I have a third-party PBX connected to a 3CX v20 via a SIP trunk.
The idea is to use 3CX as an outbound call gateway, since 3CX has another SIP trunk to a SIP Provider.

So :
  • The SIP trunk between the third-party PBX and 3CX is up and working well.
  • Internal calls between both systems work well too.
  • When users from the third-party PBX try external calls, the 3CX receives the call but doesn't forward it to the SIP provider.

3CX logs show that the call is rejected with :
  • Caller '0xxxxxxxxxx' is not found in the list of allowed extensions: ... or
  • Call(3): Failed to build divert target EndCall.DisabledByFwdRule; fail reason = NotAvailable

So it seems that 3CX does not consider the call "eligible" for outbound routing through the operator trunk, probably because it doesn't come from a local extension.
Is it possible to configure 3CX to accept calls from an external SIP trunk (not registered as a local extension) and allow them to go out via its own SIP trunk to the provider?

Thank you in advance for your help.
 
What type of trunk are you using at the 3CX end?
If you are not doing so, then try using a Bridge trunk (set as a Master), to receive registrations from the other PBX. Any calls then sent over the trunk will follow the 3CX outbound rules.
Do you have restrictions in the outbound rules?
If '0xxxxxxxxxx' is seen as the originating extension, then you may have to attempt to permit that extension to place calls, in the outbound rules.


https://www.3cx.com/docs/manual/connecting-pbx-bridges/
 
Last edited:
Hello,

Thank you for your reply.
No, I can't use Bridge Trunk because the other PBX is not a 3cx.
The SIP Trunk that connects the 2 PBXs is a generic sip. I have no restrictions on the outbound rules and adding the '0xxxxxxxxxx' in the allowed extensions doesn't work :
1749539344089.png
It seems complicated.
 
Other than it no longer being supported, it should not make any difference what the other SIP PBX is, if you want to use a Bridge trunk. Did you try? You can add it right along side the, somewhat working, existing trunk.
 
Hello,

Thank you for your reply.
No, I can't use Bridge Trunk because the other PBX is not a 3cx.
The SIP Trunk that connects the 2 PBXs is a generic sip. I have no restrictions on the outbound rules and adding the '0xxxxxxxxxx' in the allowed extensions doesn't work :
View attachment 48199
It seems complicated.

From the screen-picture I can see that you have inserted extentions in the list.
This means that extension that you put here, can dial out via this rule.
This also means that ONLY the extensions mentioned here can use this outbound rule, NOTHING else.

You would like to see calls go from trunk to trunk, but do you have another outbound rule for this ?
Or could you just try to remove the extensions you have here? (you can put them back anytime).

Just try :)
 

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