Solved SIT TRUNK incoming Call terminates after 32 seconds

[TimoM]

Hi
I have a 3CX with a generic SIP trunk to a provider, Outgoing calls are OK, but incoming calls are terminating after exactly 32 seconds. On examining the SIP call trace I found that the SIP provider is not sending ACK to respond to 200 OK being sent out.
The SIP trunk is set up behind a router which is NAT as the 3CX is on a private IP. The 3CX has single network card with Private IP on LAN (Same as the users) and the SIP provider gave a public IP to use for the 3CX, so the router was introduced.

The provider says their system will only send ACK to the IP they gave us not the one that is in the 200 OK message (the private IP). Is there a way to change the IP in the 200 OK to the public one?

The call trace is attached.

Any Help will be appreciated.

Regards
Tim

 

[YiannisH_3CX]

Hello @TimoM

I am not sure I understand your setup. I see Invites from the provider coming from a local IP Address on the 10.XX.XX.XX network and your PBX is on 192.168.XX.XX.

So why are they expecting you to use a public IP address? If the PBX sees Invites coming from a local IP address it will reply with its local IP address.

What IP are you using when making outbound calls? Do you have the public in your PBX settings?

I have deleted the logs as they contain sensitive info that should be posted online without some editing.

 

[TimoM]

Hi
Thanks for the response.
The SIP trunk is not being delivered via the public internet IP, but via the providers own separate link, to the LAN where the 3CX is operating. (see layout)

The carrier are insisting that the IN IP4 should be the 10.x.x.x not the IP of the 3CX which is 192.168.x.x, and their system will only send to the 10.x.x.x one. I tried changing settings on the SIP trunk options> "select which IP to to use in contact..." and put the 10.x.x.x IP.
The calls are OK now and the 200 OK has the 10.x.x.x IP .
Thanks for the help.
Tim

 

[YiannisH_3CX]

So both IPs are local they just need to see the local IP on their range. Glad to see you got it working