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How To Prevent Call Forward Exhaust All T1 Circuits

The voice system consists of a Callmanager 3.1(2c), and VG200 voice gateways; the VG200 connect T1 circuits to PSTN and running H.323 protocol.

User reported they could not dial in or dial out; and we found out one ip phone forward all calls to user's mobile phone, but the user setup the mobile phone forward all calls to his ip phone while the phone not in services.

It creat a call looping; and all the T1 circuits were exhausted at that monent.

Any expert can tell me how to prevent this call looping again?

I find out one parameter under callmanager services "Forward max. Hop count", the default figure is 12.

May I reduce this figure to prevent the call looping in the future?

Thanks in advance!!


Re: How To Prevent Call Forward Exhaust All T1 Circuits

The parameter you actually want is "MaxForwardsToDN". It also defaults to 12. CallManager won't detect this as a loop because it goes out to the PSTN, and thus "Forward Maximum Hop Count" will have no effect. MaxForwardsToDN will only allow that phone to forward a certain number of calls simultaneously. You might find 2 or 3 to be a more reasonable value. If you substantially lower MaxForwardsToDN, you may need to fill in the Attendant field with the DNs of selected phones you want to override this for.