It’s not often that people ask me to keep calls from being answered by a voice gateway, but recently I got privilege of addressing just that issue.

The scenario here is not all that common, but if you should find yourself in similar jam, you are going to want to send me candy and flowers for this tip.

Say that you have a voice gateway and the only reason it’s there is so that some archaic fax machine can send and receive (die, fax, die!!), and so that outgoing user 911 calls are routed out the local PSTN.

Say that for whatever reason, an FXS card was not used for the fax machine, but instead, wiring wizards split off the PSTN connection at the demarc so currently both the router and the FAX machine share dial-tone from the same line.

Say that you determine not to question the setup so much as focus on making sure that when calls come in from the PSTN, the FAX machine takes the call and the router just sits there, pretending like nothing’s going on.

Here is the magical command you need to make this happen:

voice-port 0/0/3 (or whatever voice-port your PSTN connection is cabled to)
ring number 10

This sweet little command tells the router not to pick up when the call rings in initially.   This gives the FAX machine plenty of time to jump in there and take the call without the router interference.

Granted you won’t see this everyday. If you’re lucky you may never see it.  I, on the other hand, need to have a long talk with karma…

Be sure to check out this support forum, which led me to the above solution: https://learningnetwork.cisco.com/thread/9357

Published 03/26/2012