Problem with Cisco 2610 router with Voice E&M Interface: Random DTMF Tones During Calls

[JimmySocks]

I have a problem with a Cisco 2610 being used as a voice gateway with asterisk PBX and Norstar MICS system.

Random DTMF tones are heard by the call recipient when calls are made from sip accounts (asterisk) to either extensions OR outside lines on the Norstar MICS. The originating caller (sip) does not hear these tones.

I can reproduce the tones by issuing a command that generates a lot of output on the router such as show tech-support. When listening to the call as the recipient (i.e. my cell phone) I can hear the tones while the router is building configuration and displaying the output from the command.

If I sit on a call as the recipient for a couple hours I notice the tones randomly sometimes every couple minutes, even if there are no other calls being initiated/terminated and no other lines in use.

I'd be happy to share my config if anyone wants to help me troubleshoot.

 

[whykap]

How are you converting SIP to analog E&M? have you excluded that device yet from being the issue?
Do you have any VAD (voice activity detection) turned on the cisco router?
I wonder of that is your issue, trying to keep the call up by inserting some type of noise into it? I really doubt that's the issue, but then again it is a 2610 router.
Are you running the latest IOS on the router?

You can also try debugging hte DTMF tones and see where it's coming from.

 

[JimmySocks]

I am using the 2610 router with the NM-2V Voice Network Modules and the E&M Voice Interface Cards to tie in with an E&M/DISA Trunk Cartridge in the Norstar MICS.

I am running IOS C2600 Version 12.3(26) which I believe is the latest version supported by the 2600 series. Correct me if I'm wrong...

VAD was turned on as is by default. The problem persisted even when turned off on the VOIP dial-peer.

I will try DTMF debugging next.

I get the sense from you reply that you're not surprised I'm having issues with a 2610 router? I had tried using a 2621 previous to the 2610 and it had an issue with a horrible crackling. The crackling would start anywhere from 2 days to 2 weeks after a reload and continue until the next reload. I had the same issue with the random DTMF tone on the 2610 as well. I'm getting the sense that maybe these routers are just faulty?

Is there another router you would recommend for VOIP to POTS? The 3700 supports the NM-2V Voice Network Modules but I know even the 3700 series is EOL so maybe there's another solution altogether?