Prohibit dialing out on some channels of digium Card

Good Day All,

I have installed a Digium TDM400P running asterisk 11.7.0. I have successfully managed to install the card and I am making and receiving calls just fine. However, I would like to be able to restrict incoming calls on one channel of the dial card and only enable outgoing calls on said channel. Reason for this, we have 2 analogue lines one is for voice and one for fax, I would like to have the fax line double as a voice line when we need it, but I would still to have the fax machine’s setup to remain as it is. Basically what I plan on doing is splitting the fax line and have one drop connected directly to the fax and another to the pbx, but I do not want the PBX to answer any incoming calls on the fax line. I have done some research and I see where asterisk has the ability to handle fax, but, I would rather not go this route right now. Any assistance you guys can provide would be much appreciated.


If you haven’t already, assign a DID to the fax channel using “DAHDI Channel DIDs”. Then create an inbound route that catches the DID of the fax channel and use the “pause before answer” field to prevent the pbx from answering.

Inbound DID module is for channel based call routing.

Put your outbound channels in a different group than the inbound. Then you can route at that level.

The only problem I see is if the fax is in use, I don’t think there is anything to prevent the TDM400P trying to access the fax line for an outbound call.


Guess I’m confused…

Header says “Prohibit dialing out…” while body says “I would like to be able to restrict incoming calls on one channel of the dial card and only enable outgoing calls on said channel.”

Which one is it…or do you need both?


Thanks for the fast response guys , yes you are correct there is an error in the header, I want to be able to dial out on the fax line and have the PBX not answer incoming calls on said line.

I should have also stated that I am a complete novice to this kinda stuff (as you guys could probably tell) could you say how do I do this?

And with that said would the firs suggestion now work?

For outbound, organize your dahdi channels into a group G0 or g0 that will hunt terminally up or down as appropriate, use that g0 or G0 for your outbound calls.

Set up pseudo DID’s for the analog lines , send the “voice” line to what normally answers, send the FAX line to “terminate call” -> “Play ring tones to the caller until they hangup”, bridge that copper pair to your fax machine.

Do it the right way and put an FXS port on the TDM400, connect the FAX machine to that. Both lines should be under control of PBX to work right.

Thanks for the feedback guys, I haven’t gotten a chance to fully implement as yet but when I do I will make sure to share with the community.