DTMF and Symmetric NAT
 

Having recently experienced some voice quality problems with a couple of Providers, I followed the post " How to Improve Your Voice Quality ".

I changed my settings as per the post i.e symmetric NAT NO, Optimise Audio YES and indeed call quality did improve.

However, I now find DTMF is not being recognised if I make calls to numbers which require " Press 1 for Sales etc ".

I have changed back to symmetric NAT Yes and Optimise Audio No and all works perfectly.

Why would the NAT setting block DTMF ? Any help gratefully received.

Best regards

Grahame

I suppose this issue is not related to NAT directly.
Just try to change DTMF settings (rfc2833 vs SIP INFO) on your side and check the result.

Thanks for the reply.

I'm set on my side to RFC 2833 ( default ). The only changes I can make are to PCM or SIP INFO.

Did you mean change to SIP INFO ?

Grahame

yeah, try changing those DTMF settings to one of the other two when you have the audio optimized; it might work better

Update: I imagine it could be anything. It would take a network engineer and a fat wallet to ever truly get to the bottom of various bugs in the system. Glad to see it was easily resolved.

I have reset Symmetric NAT to No and Voice Optimisation to Yes.

I have tried DTMF as PCM or SIP INFO on my ATA ( ZyXel P2002L ) and IVR calls work fine using either.

Why this should work and RFC 2833 does not I have no idea.

Many thanks for your help

Best regards

Grahame