Transfer incoming call to another trunk and disconnect initial trunk?

Hi Guys,

Not sure if what I’d like to do is possible or not but please en-light me if you can:

Say I receive a call into an extension through a given provider (TRUNK 1), I want to transfer the call to another provider (TRUNK 2) and disconnect the first provider from the call.

Specifically, I have configured a GSM Gateway to send SMS messages and its working fine. If some one happens to dial the GSM number for a voice call, I would like to transfer it over to another line/trunk/provider and disconnect the caller from the GSM line so as not to tie up that line. Is this at all possible? How?


Not possible, You can’t move the incoming leg so all trunk to trunk transfers take two trunks (except in the rare case of ISDN lines and SIP trunks that will accept diversion messages but this doesn’t apply to your case. I added this info in case someone else searches and finds this thread).

Though Skyking is of course correct, here are some possible workarounds that may be better than nothing.

  1. On the GSM line(s), set up forwarding for voice calls to a DID you have on TRUNK 2. The GSM operator will normally charge airtime for the forwarded calls, but if your plan is unlimited or has more minutes than you normally use, this may make economic sense.

  2. Set up the GSM line so callers hear a brief message advising them to call another number. You could use the GSM operator’s voicemail greeting, or play it from the PBX.

  3. Your gateway may offer an interface that allows you to transfer calls, as you can do with many operators from most smartphones. You’ll usually still be charged airtime as in (1).

  4. When the gateway is busy, the PBX could send the SMS via a pay-per-message provider.

You could also use Callback. Play a message to inbound calls on the GSM trunk then hang up. Have the PBX use Callback to phone the caller back on your other trunk.

Hi Guys,
Thank you all for the advice.I decided to play a message in the GSM line asking callers to call another number for voice communications. It just seemed the quickest way to free my GSM line which is of course my main concern.