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New Member

T1 CAS Authentication Code

I have a problem breaking DTMF tone on a T1 CAS link from a carrier that has carrier side Authentication Codes in place. What this does is generate a tone after the trunk is sized and the user inputs his 5 digit code and once accepted it allows the call out. This is used for billing at the customer request. I have the below listed details.

Any assistance is appreciated.


CallManager - CM 3.2(2c)SPH and Engineering Special 46

Gateway - 3745 (MGCP) with IOS version Version 12.2(15)T


controller T1 1/1

framing sf

linecode b8zs

cablelength short 133

ds0-group 1 timeslots 1-24 type e&m-wink-start

voice-port 1/1:1


mgcp call-agent 2427 service-type mgcp version 0.1

mgcp dtmf-relay voip codec all mode out-of-band

mgcp rtp unreachable timeout 1000 action notify

mgcp playout adaptive 60 40 200

mgcp package-capability rtp-package

no mgcp package-capability res-package

mgcp package-capability sst-package

no mgcp timer receive-rtcp

mgcp sdp simple

mgcp fax t38 ecm

mgcp fax t38 inhibit

mgcp rtp payload-type g726r16 static

dial-peer voice 1023 pots

application mgcpapp

dial-peer voice 999111 pots

application mgcpapp

port 1/1:1

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Cisco Employee

Re: T1 CAS Authentication Code

With MGCP, you will need to add the 5 digit code as a prefix for all calls leaving this endpoint in callmanager. This should work as long as they are looking for the digits after the wink.

New Member

Re: T1 CAS Authentication Code

Not possible, each person in this 1000 phone location has their own code for billing back to the departments...

Any other suggestions?



Re: T1 CAS Authentication Code

If you have to /prepend/ the billing code to the phone number, there are a couple of solutions.

You might try a route pattern "9." with strip-predot out that channelized T1. I'm pretty sure this will result in you just seizing a trunk on that T1 and sending no digits. The audio path will be cut through to the user and they should hear dialtone, and then they enter their PIN, and then dial normally - but the digits will be collected by the PSTN switch directly instead of by CallManager. I have not actually tried this, but I think it should work with MGCP. The disadvantage is that CallManager will have no idea what you called, so you will have no meaningful CDR records, and you will be almost entirely reliant on your carrier's reporting.

If the PIN is of a consistent length (say, always 5 digits) and you don't need to pause between PIN entry and dialing the number, you can use a route pattern like "9.XXXXX@", which will collect 5 digits for the PIN and then allow you to dial anything in the NANP normally. This is just like the usual "9.@", but with a PIN. I'm not sure if you can introduce a pause when outpulsing that on the channelized T1, so you may or may not be in trouble if you have to pause between the PIN and dialing.

I really can't envision how the channelized T1 can interactively prompt you for a PIN while using E&M wink start, so I may not be correctly understanding how your carrier has this set up.

If you have to post-dial the billing code after dialing the number (which is the way I've seen it work in other environments), you shouldn't really have to do anything out of the ordinary. The call goes out normally so far as CallManager knows, the user will hear the prompt for their PIN and dial it in, and the call will proceed.

New Member

Re: T1 CAS Authentication Code

Your last comment is correct the dial out is similar to below:

Dial Pattern 91XXXXXXXXXX


9 19724567372 345665 (user code)

but when the user inputs the user code the tone does not break the tone.

My question, has Anyone ever gotten this to work in a CallManager environment over a CAS or PRI circuit?



Re: T1 CAS Authentication Code

We've seen it work, and it should work for you. It sounds like the carrier isn't "hearing" your DTMF tones for whatever reason.

Verify that you have DTMF-relay configured on your gateway (mgcp dtmf-relay voip codec all mode out-of-band). This should make sure that the tone gets sent out the channelized T1 loud and clear.

You could also setting a few DB of negative attenuation, meaning gain, to see if it's too quiet for your carrier as-is. Try "output attenuation -3" or thereabout on your voice-port.

New Member

Re: T1 CAS Authentication Code


Check out:

CSCdx52074 CCM Does Not Forward Access Codes To MGCP Gateway

CSCdx52074 is fixed in ES46. So you should not be seeing this one. However, to verify you can run mgcp debugs to see if the digits are received from the Call Manger.

CSCea19218 MGCP gateway does not playout DTMF during EM_WAIT_FOR_ANSWER state.

CSCea19218 is probably the culprit. Not fixed in 122-15.T. It is resolved in 122-13.T3 but this code has CSCeb10204 which is not yet resolved.

FWIW, these issues are all MGCP/T1 CAS related and do not happen with H.323.

The issue with CSCea19218 is that when the users are prompted with the Tone to enter the access code, the state of the call is not Connected but rather EM_WAIT_FOR_ANSWER and the gateway does not outpulse the DTMF tones while in this state.

I have gotten this to work with MGCP and PRI.



New Member

Re: T1 CAS Authentication Code

Updated the 3745 to IOS c3745-is-mz.123-1.bin and resolved the CAS DTMF Authentication problem.

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