Immediate "Ringing you back" when doing unsupervised transfer

[petr.necas]

There is a strange issue with call transfers. When extension A calls extension B and B transfers the call to extension C (unsupervised transfer), immediately after B hangs up it receives "RINGING YOU BACK" call.

All phones have the same COS with the "No Answer Recall Timer" option set to 17.

Same or similar issue is described here http://mitelforums.com/forum/index.php?topic=5614.msg25233#msg25233, but changing the "Public Network To Public Network Connection Allowed" option to Yes for the phones COS does not help.

Any ideas?

[x-man]

Is the trunk COS set for the same and is this for internal calls or for trunk calls being transferred and what are the trunks if external call transfers?

[petr.necas]

It can be reproduced even without any trunk being involved, but when calling to B from outside it is the same problem.

Yes, the trunk "Public Network To Public Network Connection Allowed" option is set to Yes.

We have noticed that it can only be reproducted if C is another branch office (and on another subnet), when C is in the same office it works fine.

[ralph]

This normally happens when the line being transferred is not allowed to connect to the phone being transferred to.
This can be because of tenanting or interconnect restrictions. 

What happens when the call is supervised?
If you do a conf call 1st and then drop out what happens?
Can the phone call it directly rather than being transferred?

Ralph

[petr.necas]

Thank you for your answers.

There are no interconnect restrictions and no tenanting programmed, the extension A can call directly to C with no issues.

Supervised transfers work just fine.

[ralph]

Are all the phones registered to the same controller?

Ralph

[petr.necas]

Yes, there is just one controller running latest release 14.0.0.97.

[x-man]

MGB and SIP trunks involved?

[petr.necas]

Yes, but MBG and SIP trunk has nothing to do with this issue.

Mitel support pointed me to the source of the problem. Let me explain:

The customer did not want to use dialing prefix. So to dial Prague number they just want to dial e.g. 2xxxxxxxx, not 02xxxxxxxx. But they also have extensions 201 and 202, so to allow dialing these extensions I had to add 2 new rules in Digits Dialed 201xxxxxx and 202xxxxxxx in addition to existing 2+8 digits (I hate this setup but that's the way it is configured now). Calling to 201 and 202 works fine, except unsupervised transfers to 201 or 202. A solution could be either to change the extensions to avoid the dialing conflict or use # (end of dial) during the transfers (201# and 202#). Learning new things every day :-).

[ralph]

Yes.  I should have thought of that one.

Another thing you can do is to have the user wait until they hear ringing before they release the call.

Ralph

[petr.necas]

Good point. Thank you.