Unanswered Question
Jan 10th, 2008

I am a beginner to intermediate level in the VOIP world, so please excuse any misunderstanding. Can someone tell me what CAS MF is, is it different from "CAS"? I have a friend that work at small VOIP providor and he said he has issues interfacing to a customer's Avaya PBX...I will post this question once I get some clarification on what CAS MF is.

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 3 (1 ratings)
Paolo Bevilacqua Thu, 01/10/2008 - 16:51

MF stands for (signaling) multi frequency. That is not the same as DTMF that are the tones sent by a normal keypad. Normally, CAS is DTMF, however CAS is a generic term, there are variants.

MF signaling was used on trunks between COs, not on circuits to subscribers. Historical note, in the beginning, some people were able to exploit the tones (seizing the trunk) to make free calls and they were known as phone hackers.

Anyway, if the Avaya PBX works when connected to PSTN it will work connected to a cisco router.

Hope this helps, please rate post if it does!,/i>

jeremy.rambarran Thu, 01/10/2008 - 18:26

Excellent! Thank you for the reply.

This is just a scnerio, since I do not have all the details or access to the equipment (sorry if it may be to vague):

We are trying to interface a Cisco 2821 with an NMHDV-2 to an AVAYA PBX. There is an alarm on both ends, seems not to be peering properly. We test both ends with a loopback and it comes up fine. The cable tested fine. Changed out the cable, same thing. Put on a monitoring tool and nothing tells what the issue is. From a troubleshooting standpoint, what are things that should be checked considering all that has been done above? This is using CAS

Where can I learn more about this stuff, and about CAS MF, CAS? I do not see much documentation online, or maybe I am not looking in the right place.

Thank you in advance!

Paolo Bevilacqua Fri, 01/11/2008 - 11:06


first make sure you use a proper T1 cross cable, not ethernet cross cable.

Then send output of "show controller T1" and your config of course.

There is stuff about CAS available, but try to do without it if possible. CAS is being replace by CCS (PRI) and can be considered legact to all effects.

Hope this helps, please rate post if it does!

jeremy.rambarran Fri, 01/11/2008 - 12:55

We are finding alot of legacy PBX's that only support CAS MF, even CAS Pulse. Some don't even want to talk about replacing their PBX or go with a hosted solution. Do you know where I can find more info on CAS? I too would rather use CCS

Paolo Bevilacqua Fri, 01/11/2008 - 14:51


search cco for "configuring T1 cas". If you have a specific case, post the data here, because everything can be made to work with the right configuration.


This Discussion