3cx and IP authenticated SIP trunks...

[digital30]

Hi,

I have a potential customer who currently have Gamma SIP trunks. I have set up 3cx to test this as a proof of concept for them but I am receiving a 403 forbidden message back from Gamma when trying to make outbound calls. Gamma have done a trace of the call and they are seeing the internal IP address in the contact header. Does anyone know if there is something I can specify in the outbound parameters to make that display the external IP address?

Initially i thought this might be a NAT issue but there are NAT rules in place. Has anyone else used Gamma via 3cx?

 

[lneblett]

Go to the VoIP Providers section on the left hand side of the console and select the desired provider. Then select the advanced tab at the top. You will then see the registration settings where you can change as needed.

 

[digital30]

Thanks for the reply....Sorry for not explaining in the original post but these are IP authenticated SIP trunks. So no registration required.

 

[leejor]

Did you come across these sites in your searches?

http://phillipcooper.co.uk/2012/02/configuring-a-gamma-voip-provider-trunk/

http://www.afrank.co.uk/it-telecoms/17-3cx

If required, in 3CX, under the VoIP provider, you can customize the Outbound Parameters .

 

[Deepest]

Hi There i had a similar issue with an ip registered sip trunk. The trunk would register but everytime i tried to make a call i would get an error. On testing with the provider we came to the conclusion that the sip header was getting modified by 3cx and causing the issue. What we had to do was to remove every single entry and setting on the outbound parameters of the sip trunk.
After we did this it ran 100 %.

 

[lneblett]

I may be wrong, but in the section I originally specified, you can also select the condition needed.

By that I mean that you can select the options that eliminate the need to register altogether (look at the pull down box), yet you can still alter the IP address in the contact field. I assume that you can set to "do not require" for registration and still input the IP desired/needed in the "contact field".

I am uncertain if the two are mutually dependent upon one another. But if independent, then maybe this is the trick. A wireshark would confirm.

 

[digital30]

Thanks for all the feedback....i've been able to focus a bit more time on this today testing wise.

I updated the IP address to point to one of our test adsl lines in the office which has a nasty cheapo router on the end and it worked. I requested a wireshark trace from Gamma and it shows the via has a matching address to the rest of the contact header...the external address. I switched it back to the customers IP and i'm getting the same as above on the wireshark trace.

The customer has a draytek 2960...I'm not sure why the Via would continue to display the internal ip if it's gone through NAT on the firewall...i've had a play with the outbound parameters but nothing updates this field. I have seen the articles about adding a second adapter with the external ip directly assigned to it but this seems like a bit of an overcomplication, not to mention the fact they are using all the ports on their firewall for their different vLans.