Trunk Setup

[Ryan Schroller]

To whom it my concern,

I have been trying to do some testing to see if 3CX would be a good platform to migrate to from FreePBX. I still cannot seem to make our SIP trunks work with 3CX. I have tried just about everything, including running working FreePBX backup through the conversion tool to see if that would work. I cannot seem to restore from the converted backup, as it says it
is not a viable backup.

Here is the issue that I think is giving us the problems with registering this SIP trunk.

Here is a TCP dump from a working FreePBX:

9:43:47.328183 IP (tos 0x60, ttl 64, id 45793, offset 0, flags [none], proto U$
X.84.79.22.sip > X.84.77.210.sip: [bad udp cksum 9b3c!] SIP, length: 416
REGISTER sip:X.84.79.22 SIP/2.0
Via: SIP/2.0/UDP X.84.79.22:5060;branch=z9hG4bK0c7dddb9;rport
Max-Forwards: 70
From: <sip:[email protected]>;tag=as30ee77c5
To: <sip:[email protected]>
Call-ID: [email protected]
CSeq: 102 REGISTER
Supported: replaces, timer
User-Agent: FPBX-13.0.195.13(13.23.1)
Expires: 120
Contact: <sip:[email protected]:5060>
Content-Length: 0

Here is a TCP dump from 3CX


192.168.2.11.sip > 208.84.77.210.sip: [bad udp cksum 0xe32a -> 0x4b8d!] SIP, length: 567
REGISTER sip:X.84.77.210:5060 SIP/2.0
Via: SIP/2.0/UDP X.168.2.11:5060;branch=z9hG4bK-524287-1---74b84b0722ba561f;rport
Max-Forwards: 70
Contact: <sip:[email protected]:5060;rinstance=821fd3fee80ce31b>
To: <sip:[email protected]:5060>
From: <sip:[email protected]:5060>;tag=46e09852
Call-ID: HQo0gVXnzc3zrpeyDjJBTQ..
CSeq: 1 REGISTER
Expires: 600
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REGISTER, SUBSCRIBE, NOTIFY, REFER, INFO, MESSAGE, UPDATE
Supported: replaces, timer
User-Agent: 3CXPhoneSystem 15.5.15502.6 (15502)
Content-Length: 0

As you can see, the to and from are different. 3CX has our trunk IP (X.84.77.210) in the to and from. FreePBX has the PBX IP (X.84.79.22) in the to and from.

 

[Saqqara]

Who is the supplier of your sip trunk ?

 

[Lee Cramman]

What platform are you running on and is it physical or virtual?

Have you ticked "Put Public IP in SIP VIA Header" (and added your IP) in the trunk settings?

Is your SIP trunk provider approved by 3CX?

Is your SIP trunk provider using IP address based security and your packets now appear to be originating from a different address?

 

[Ryan Schroller]

Who is the supplier of your sip trunk ?

I work for a small ISP. We have several SIP trunks to FreePBX appliances, which are working currently. We cannot seem to make it work with 3CX

 

[Ryan Schroller]

What platform are you running on and is it physical or virtual?

Have you ticked "Put Public IP in SIP VIA Header" (and added your IP) in the trunk settings?

Is your SIP trunk provider approved by 3CX?

Is your SIP trunk provider using IP address based security and your packets now appear to be originating from a different address?

We have messed with the public IP setting. I see in the packet flow that it is trying to use the internal private IP, but that is not the real issue.

SIP trunk is not approved by 3CX. We are a small ISP. We have several SIP trunks that are working well with FreePBX. No luck with 3CX. So much for open source I guess.

It is Auth based, so we have a user/password that they give us. It is also tied to an IP when they setup the trunk.

 

[cobaltit]

Have you ticked "Put Public IP in SIP VIA Header" (and added your IP) in the trunk settings?

That's not going to change the registration string, just the the VIA string header as it states.

@Ryan Schroller

If the difference is the host part have you tried changing the settings on the trunk so 3CX sends the PBX IP instead of the registrar IP? Seems like the logical answer if that's the difference between a working and not working setup.

 

[Lee Cramman]

That's not going to change the registration string, just the the VIA string header as it states.

@Ryan Schroller

If the difference is the host part have you tried changing the settings on the trunk so 3CX sends the PBX IP instead of the registrar IP? Seems like the logical answer if that's the difference between a working and not working setup.

You are, as usual, correct!

@Ryan Schroller

With a non-approved SIP trunk provider it's often worth talking to their tech support as they can usually tell you straight away what is wrong with the data your PBX is presenting to them and what they expect to see in order for it to be valid.

This isn't really anything to do with open / closed source. I haven't come across a provider that 3CX can't work with, it's just that non-approved (and some approved!) trunks require a bit of tinkering with the parameters page in order to present the data in the way your provider is expecting and you can get better support from 3CX if they are on the approved list.