Creating "Ring Groups" with Local channel

I am having a special requests about ring groups (when a call comes in, multiple SIP phones ring simultaniously), so I need to use the Local channel for implementation of the dialplan. This is the code:

exten => 1100,1,Dial(Local/1101@interal_calls&Local/1103@interal_calls,40,t)
exten => 1100,n,Hangup()

;*** Peers that ring - in case nobody answers the call, the missed call is not listed on the phone ***
exten => 1101,1,Dial(SIP/2&SIP/3,40,tc)
exten => 1101,n,Hangup()

;*** Peers that ring - in case nobody answers the call, the missed call is listed on the phone ***
exten => 1103,1,SIPAddHeader(Alert-Info: info=<Bellcore-dr5>)
exten => 1103,n,Dial(SIP/1,40,t)
exten => 1103,n,Hangup()

The code works as expected in case of unanswered call. Because of the Dial “c” flag, the missed call is listed only on phone 1. The problem is if the call is answered on phones 2 and 3 - the phone 1 lists a missed call in this case. This is very wrong.

The reason for this is that the Reason header is not sent in SIP Cancel to phone 1 in case when phone 2 or phone 3 answer the call.

Is this a bug in Asterisk or can I correct the Dialplan in any way to fix this problem?

I tried using the /n on the end of the Local channel with little success.

You would need c on the top level Dial for this to stand a chance of working. I don’t know if it will behave as you expect, even then.

No, “c” on the Dial() at extension 1100 causes that even unanswered calls are not listed on any phone. So in this case the “Reason: Answered elswhere” is sent always in SIP Cancel messages.

This test was made on Asterisk 1.8.24.

I tried the same setup on Asterisk 11.7 and the feature works as expected (same as implementing a Ring Group with Dial and &). So this issue is resolved in the new Asterisk version. But I am not sure for Asterisk 1.8 - should I report this as a bug?