Solved Generic Sip Trunk disconnects until inbound call

[Morgan Schulz]

I have a test system going with a centurylink SIP trunk. It's purely IP based, no registration. The connection seems to time out after a while. When this happens, I can't call out. I get an error message:
SIP Server/Call Manager ID: 12294
Call or Registration to [redacted]@(Ln.10001@CLink Test) has failed. 0.0.0.0 replied: 408 Request Timeout; internal

When a call comes inbound to the system, the connection to the trunk is re-established and I can call out again. I'm not sure where to start with this problem, any ideas?

 

[YiannisH_3CX]

Hello @Morgan Schulz

Please note that the tested and supported type of trunk from Century link is authentication based and as we have not tested their IP based service we cannot guarantee full compatibility.
https://www.3cx.com/docs/centurylink-business-sip-trunk/

Having said that i think your issue has to do with your firewall as IP based trunks do not register and there is no constant connection between the PBX and the provider. It looks like after a period if inactivity the firewall blocks the connection until an incoming call arrives which triggers the firewall and allows the connection.
Also not sure this is relevant but another forum user posted a guide on how to set up an IP based account from Centurylink.
https://www.3cx.com/community/threads/centurylink-level3-sip-trunk-setup.57362/

 

[Morgan Schulz]

Hello @Morgan Schulz

Please note that the tested and supported type of trunk from Century link is authentication based and as we have not tested their IP based service we cannot guarantee full compatibility.
https://www.3cx.com/docs/centurylink-business-sip-trunk/

Having said that i think your issue has to do with your firewall as IP based trunks do not register and there is no constant connection between the PBX and the provider. It looks like after a period if inactivity the firewall blocks the connection until an incoming call arrives which triggers the firewall and allows the connection.
Also not sure this is relevant but another forum user posted a guide on how to set up an IP based account from Centurylink.
https://www.3cx.com/community/threads/centurylink-level3-sip-trunk-setup.57362/

Thanks! I saw the other article, it was very helpful. Let me ask you this, does the re-register timeout field require a value? Because I'd say that's about the amount of time it takes before disconnecting.

 

[YiannisH_3CX]

That field applies only to Register based providers as it is only used during registration so it does not apply to IP based providers.

 

[Morgan Schulz]

That field applies only to Register based providers as it is only used during registration so it does not apply to IP based providers.

Hello @Morgan Schulz

Please note that the tested and supported type of trunk from Century link is authentication based and as we have not tested their IP based service we cannot guarantee full compatibility.
https://www.3cx.com/docs/centurylink-business-sip-trunk/

Having said that i think your issue has to do with your firewall as IP based trunks do not register and there is no constant connection between the PBX and the provider. It looks like after a period if inactivity the firewall blocks the connection until an incoming call arrives which triggers the firewall and allows the connection.
Also not sure this is relevant but another forum user posted a guide on how to set up an IP based account from Centurylink.
https://www.3cx.com/community/threads/centurylink-level3-sip-trunk-setup.57362/

Score another one for YiannisH_3CX, it was a firewall issue. As long as a session was established, we could communicate in either direction. Thanks again!

 

[YiannisH_3CX]

Glad to see the issue has been resolved and thank you for updating the thread with your solution