Prepend automatically replaced by Extension Number - Unable to make outbound call

[robert5168]

Hi Community,

I migrated to v15.5 from v12 in the past weekend (Thanks to 3CX's generous offer and v15.5 is such a great product).

However, I have encountered something really strange. 3 or 4 extensions out of about 30+ extensions (remote direct STUN extension) have not been able to make outbound calls after the upgrade to v15.5. The system kept replying "Call forbidden by administrator" when making outbound calls.

I looked up the Activity Log and see something like:
"Call to T:Line:10002>>622687360255787677@[Dev:sip:0732167937@ISP_IP:5060] from L:452.1[Extn:988] failed, cause: Cause: 403 Forbidden/INVITE from ISP_IP:5060

(I replaced actual IP with ISP IP)

I called my ISP and asked them to trace the call. They said the Prepend (62268736 in this case) in the Outbound rule is replaced by the extension number (ie. 201) in the message sent to them. It then results in failed authorization for the call.

Has anyone encountered similar problems at all? Thanks ahead.

 

[robert5168]

Update:
1. The problem occurs on OLD extensions migrated from v12 and also occurs on NEWLY created extensions in v15.5. (All remote direct STUN)
2. I don't think it is the problem of my IP Phone, since it occurs to 3CX Android Phone, supported Yealink and unsupported Cisco ATA.
3. If I delete the extension in 3CX System and recreate the extension, it then is able to make outbound calls with the exact same setting.
4. My own extension (on 3CX Android) has been able to make outbound calls, but it just failed on me NOW. After deleting and recreating my own extension, it is now able to make outbound calls.

I know I can keep deleting and recreating extensions and it may work just fine... but does anyone know the reason behind it? Just maybe I can have a permanent solution to the problem.

 

[robert5168]

Additional Remark: (Sorry, trying to explain the situation as fully as I can)
Every remote extension is located in different location with different WAN IP, so I don't think it is the issue of extensions fighting for the same SIP or RTP ports.

 

[YiannisH_3CX]

Hello @robert5168

Are all the extensions using the same outbound rule? You run a capture on the PBX and compare a working and a non working call to see the difference and what is causing the issue.

 

[leejor]

What does the Activity Log show (the dialled number) originating from the set? The initial Invite? I have to assume it matches an outbound rule. If the extension number is somehow being included in the digits sent to your provider, it (the log, similar to what you posted) should show if the prepend is being replaced by it. I'm wondering if it has anything to do with the 3CX trunk options dealing with where caller ID is taken, on that trunk group. I don't really see how the extension number would otherwise be involved if it is not dialled, or as a part of an outbound rule.