Strange CANCEL reason text

[pongaro]

Hello,

I found a strange issue with forked calls handling with my SIP trunk provider.

When the incoming call is picked up on a remote phone that connects direct to the SIP trunk, I got "missed calls" on all phones (all in the same ring group) that sit behind the 3CX PBX v16.

With Wireshark, I found that instead of getting the classical RFC3326 CANCEL reason text="Call completed elsewhere", the 3CX PBX receives CANCEL reason text="INVITE Accepted Elsewhere". See attached screenshot.



The reason for CANCEL is not propagated to the phones behind the PBX at all.

Do you think that it could be the reason for the occurence of "missed calls" ?

Is there a way to configure the 3CX PBX to cope with the unusual CANCEL reason text, and thus preventing the occurence of "missed calls" ?

Many thanks for your support.

 

[Evolute IT]

Hello,

I found a strange issue with forked calls handling with my SIP trunk provider.

When the incoming call is picked up on a remote phone that connects direct to the SIP trunk, I got "missed calls" on all phones (all in the same ring group) that sit behind the 3CX PBX v16.

With Wireshark, I found that instead of getting the classical RFC3326 CANCEL reason text="Call completed elsewhere", the 3CX PBX receives CANCEL reason text="INVITE Accepted Elsewhere". See attached screenshot.

View attachment 12543

The reason for CANCEL is not propagated to the phones behind the PBX at all.

Do you think that it could be the reason for the occurence of "missed calls" ?

Is there a way to configure the 3CX PBX to cope with the unusual CANCEL reason text, and thus preventing the occurence of "missed calls" ?

Many thanks for your support.

What is the SIP provider you're using? Is it a certified one?

 

[pongaro]

Hello,

It is the most important telco operator in Switzerland ...

Thanks.

 

[craigreilly]

Hello,

It is the most important telco operator in Switzerland ...

Thanks.

Doesn't answer if they are certified with 3cx or not.

 

[leejor]

You are registering a set and a 3CX trunk to the same account, as your provider allows SIP forking. This is not a "normal' set-up with one registration being that of a PBX trunk.. I'm assuming that 3CX does not pass along the "Call answered elsewhere" message because it would not normally expect to receive it. This could be an oversight, or intentional. The proper way to set this up (if you don't want the missed call messages), is to have the "other" set as an extension off the PBX (part of the ring group?).