[asterisk-users] double DTMF digits

[Andres]

On 8/26/2010 2:55 PM, M S wrote:
> Hi,
>
> I've been getting complaints lately that callers to my IVR are 
> pressing a digit once but the system is responding as if they pressed 
> it twice (once for each of two consecutive menus).
> I'm using an AGI script and logging all DTMF entries - and to the 
> script, at least, it looks like the digit is being pressed twice.  The 
> TN being called is a VOIP number (provided by Flowroute) and being 
> forwarded via SIP to my asterisk 1.6.2.4 server.  The dtmfmode is set 
> to rfc28333 in sip.conf.
>
> The first time this happened, I figured the caller pressed the number 
> twice without realizing it.  It's happening to too many people for 
> that to be plausible anymore.  I also experienced it once myself, 
> months ago, when I entered my tn as 1234567890 and had it read back to 
> me as 1122334455.
>
> Can anyone give me some pointers where to start troubleshooting?  Can 
> overloading a system cause such an error?
>
> Thanks,
I have seen this before.  Upon careful analisys we saw that the far end 
was sending the digits in RFC2833 plus SIP INFO (or Inband, I can't 
remember).  Thus Asterisk detected double digits.  The solution was to 
ask the remote end to only send RFC2833.

Andres
http://www.telesip.net