DTMF Issues - SIP Trunks

[Tech Electronics]

Guys,

Does anyone have a good way to track down and resolve issues with DTMF over SIP Trunks on a MiVoice Business Express?

The system doesn't have this issue with all Auto Attendants and it isn't always the same button press. The MiVB-X is using its internal MBG to talk to an SBC on the same VLAN and for the most part I have not been able to replicate the issue myself, but it is happening enough with the customer that they want us to look into it as they see it as a problem.

I had them try to call our test number it works fine every time from their phone as well as any phone on the system. I know that the DTMF Payload is 101, but I can't tell whether or not it is set for RFC-2833 or whether it is in-band or out-of-band. I am at a total loss as to how to proceed on a 3300 with this issue.

Thanks,

TE

[x-man]

I think you are going to have to do a wireshark trace till it happens then you can look to see why its failing. You'll need to wireshark the SBC I suspect. Last time I had a sinilar issue on SIP tunks like this it turned out the firewall had SIP helpers enabled and although most calls were fine at least one service (a conference setup remotely) had issues. In that case dialling into the conference just returned silence. turned off the SIP helper and everything was hunky dory.

[martyn]

I'd set a continuous wireshark trace running on the MBG with it splitting the files in to a reasonable size, and then get users to report when they have issues, and what number they are calling to. From there you can grab the trace and analyse the call to see what's being/not being negotiated.

[eugenej]

Guys,

Does anyone have a good way to track down and resolve issues with DTMF over SIP Trunks on a MiVoice Business Express?

The system doesn't have this issue with all Auto Attendants and it isn't always the same button press. The MiVB-X is using its internal MBG to talk to an SBC on the same VLAN and for the most part I have not been able to replicate the issue myself, but it is happening enough with the customer that they want us to look into it as they see it as a problem.

I had them try to call our test number it works fine every time from their phone as well as any phone on the system. I know that the DTMF Payload is 101, but I can't tell whether or not it is set for RFC-2833 or whether it is in-band or out-of-band. I am at a total loss as to how to proceed on a 3300 with this issue.

Thanks,

TE

You'll have to start with a trace. Mitel supports only RFC 2833 for DTMF. That is out of band as RTP event packets. Inband is normally tones generated and then decoded by the equipment, similar to fax.