Refusing Incoming calls to a VG while preserving existing ones?

Unanswered Question
Apr 23rd, 2007

We have a 24/7 operation, with two 2821s with VWIC-2MFT-T1s acting as Voice Gateways. Each has an multiple ISDN PRIs to the Telco that are used for incoming and outbound calls.

My question is if a Gateway has to be taken down for maintenance, is it possible to refuse incoming calls from the Telco while preserving existing calls?

Obviously this can be done on the Telco's end, but I'm wondering if it's possible to do without them getting involved. The gateways currently run MGCP but I'm converting them over to H.323 next month.

I have this problem too.
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Paolo Bevilacqua Mon, 04/23/2007 - 15:28


If you can accept to simply not answer calls, the simpler way is configuring "isdn answer1 555".

Else look at "PRI busyout" on CCO. This is dependent on the switch used.

Hope this helps, please rate post if it does!

johnnylingo Mon, 04/23/2007 - 16:03

Does "isdn answer1" only work on H.323 gateways? It didn't seem to have any effect on the MGCP-controlled PRI I tried.

Paolo Bevilacqua Mon, 04/23/2007 - 16:14

What if you on CCM route all calls to a phone that is not answered or always busy. Same effect and protocol independent :)

johnnylingo Mon, 04/23/2007 - 16:29

Hmmm...will have to try that, but I would assume the telco sees a busy from a phone and a all circuits busy from a PRI as two separate things. Along the same lines, I was thinking once converted to H.323, I could shut down the applicable dial-peers.

Paolo Bevilacqua Mon, 04/23/2007 - 17:20

No telco won't see all circuits busy, it will just return busy to all callers, one circuit at time.

Also note that with h.323 if you shutdown a DP they will cease to exist, so caller will match the default dial-peer and get a dialtone ... not exactly what you want.

With h.323 the proper method is to place a translation-profile that rejects the call for all numbers.. this is the only thing, I would think, that properly rejects a call at Q931 level.


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