Solved Unable to register to sip trunk on 3cx, despite successful registration on zoiper.

[sricharan001]

I have a 3cx pro v18 installed on my local server. I have two interfaces for 3cx - one for internet and another for voip. I am trying to configure two sip trunks -
trunk A
on internet
UDP sip,
doesnt use sip proxy,
works just fine.

trunk B
on a dedicated interface.
tcp sip,
uses sip proxy(lets say 10.x.x.x),
static routed 10.x.x.x on the server to voip interface.

Issue - trunk B doesnt get registered(403/forbidden), but works just fine on zoiper.

trunk B config
registrar - ims.foo.com:5060
sip proxy - 10.x.x.x:5060
username - [+nnnnnnnnn]
password - [password]
auth id - [username]@ims.foo.com
protocol - TCP

digging into details

what 3cx sends in REGISTER packet:
03/20/2022 1:03:56 AM - Sent registration forLc:10001(@Asterisk[<sip:[email protected]:5060/UDP>]) :ClientReg Send Req REGISTER from 0.0.0.0:0 tid=7445ac024fbeff6d Call-ID=fqHaJwAeBGCz25xn2ImlxA..: REGISTER sip:ims.foo.com:5060;transport=TCP SIP/2.0 Via: SIP/2.0/ ;branch=z9hG4bK-524287-1---7445ac024fbeff6d;rport Max-Forwards: 70 Contact: <sip:[email protected]:54000;transport=TCP;rinstance=6a91fd16c2c56027> To: <sip:[email protected]:5060;transport=TCP> From: <sip:[email protected]:5060;transport=TCP>;tag=1537d531 Call-ID: fqHaJwAeBGCz25xn2ImlxA.. CSeq: 1 REGISTER Expires: 600 Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REGISTER, SUBSCRIBE, NOTIFY, REFER, INFO, MESSAGE, UPDATE Supported: replaces, timer Content-Length: 0

what zoiper sends in REGISTER packet(successful registration):

[/B] Session Initiation Protocol (REGISTER) Request-Line: REGISTER sip:ims.foo.com:5060;transport=TCP SIP/2.0 Message Header Via: SIP/2.0/TCP 100.x.x.x:49254;branch=z9hG4bK-524287-1---3c46df2e6a2043e0;rport Max-Forwards: 70 Contact: <sip:[email protected]:49254;transport=tcp;rinstance=4a99348f73bfc683>;expires=0 To: <sip:[email protected]:5060;transport=TCP> From: <sip:[email protected]:5060;transport=TCP>;tag=e038d941 Call-ID: di6rIQLteemnPw4W8goUuw.. [Generated Call-ID: di6rIQLteemnPw4W8goUuw..] CSeq: 3 REGISTER Allow: INVITE, ACK, CANCEL, BYE, NOTIFY, REFER, MESSAGE, OPTIONS, INFO, SUBSCRIBE User-Agent: Z 5.5.8 v2.10.17.2 [truncated]Authorization: Digest username="[email protected]",realm="ims.foo.com",nonce="M7E37qr5Qp00V0mIqElfpQ==",uri="sip:ims.foo.com:5060;transport=TCP",response="170e86d1d348bbaa1ee2efb5be6cfeb0",cnonce="e4d5208056850c8 Allow-Events: presence, kpml, talk Content-Length: 0 [B]

can somebody untangle this for me, please?

 

[YiannisH_3CX]

Hello @sricharan001

It looks like your provider needs 3-way authentication which you should enable on 3CX.
Also you are comparing different packets from 3CX and Zoiper. You are looking at the first register message from 3CX before the authentication reply from the provider but from Zoiper you are looking at the register containing the authentication. So find the same from 3CX and compare them to see what is different.
If I had to guess I would say its probably the credentials you need to use as 3-Way authentication. Try using the "auth id - [username]@ims.foo.com" as your 3-way Authentication.

 

[sricharan001]

Hello @sricharan001

It looks like your provider needs 3-way authentication which you should enable on 3CX.
Also you are comparing different packets from 3CX and Zoiper. You are looking at the first register message from 3CX before the authentication reply from the provider but from Zoiper you are looking at the register containing the authentication. So find the same from 3CX and compare them to see what is different.
If I had to guess I would say its probably the credentials you need to use as 3-Way authentication. Try using the "auth id - [username]@ims.foo.com" as your 3-way Authentication.

YiannishH_3CX, you are one heck of a genius! What you told is exactly right. Thanks man!

 

[YiannisH_3CX]

Glad I could assist