Asterisk SIP trunk with 3CX

Posted on 2012-08-21
Last Modified: 2014-05-05
Hey Experts,
So i am trying to create a trunk between 3CX and FreePBX (asterisk).
Sorry if my terminology is a bit off...
The Trunk is a authenticated trunk on the 3CX. Trunk user:10000.

If i go onto X-lite or another sip client i can setup a user account with ext:10000 and password and that client will register as a user through the trunk.

From FreePBX however i get a msg "Authentication failed to REGISTER" so i am guessing i just have something wrong on the Trunk settings...

Here are my FreePBX settings.
PEER Details:

host= (IP OF 3CX)
username=10000 (Trunk extension on 3CX)
secret=1234 (Trunk password)

USER Context:      10000

Registration String:10000:1234@

Anything i should change on this?
I have attached a PCAP file captured from the 3CX when trying to register. Maybe it will shed some light?  Had to change to .txt to upload just change back to pcap to open in wireshark.
Question by:tsukraw
    LVL 15

    Accepted Solution

    @ tsukraw

       Not that familiar with the 3CX but I would check a couple of things from the Asterisk side.  

       What's in your SIP configurations for localnet values ? Depending on the build it wouyld be in /etc/asterisk/sip.conf or /etc/asterisk/sip_nat.conf

       Add to the Peer definition above.

       Change your registration statement to


    Author Comment

    Correction on a typo of yours.  10000:1234@ should be 10000:1234@  there is a extra :50 in there.  And that did fix it!  It was missing the /10000 at the end!

    Thank you!

    Expert Comment

    Hello all,
    I am trying the same situation.
    Thanks to this article, it is very useful. I got the SIP trunk registered.
    However now the calls are not going through for some reason.

    When I call through the 3CX to the free PBX I get a "Not acceptable here" 488 error.
    Any tips?
    Thank you

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