[Asterisk-Users] GSM ISDN gateway to quadbri NT port under bristuffed Asterisk - where to set gain (I have unreliable inband dtmf recognition )?

[Peter Svensson]

On Tue, 21 Jun 2005, Leandro Morgado wrote:

> Steve Underwood wrote:
> > Robert Rozman wrote:
> >> I'm getting unreliable dtmf recognition (it works fine for 4-5
> >> digits, errors (duplicates) on more), when transferred inband from
> >> gsm gateway to NT port of quadbri under bristuffed Asterisk.....

We get these quite often. If there is any line noise asterisk will 
interpret it as the end of a digit and then detect the same digit again. 
We are connected to the pstn via isdn. The problem is with calls where the 
dtmf tones are a bit unclean, i.e. too much energy is in the overtones. 
Clean dtmf tones seem to be much more resistant to line noise.

Out other systems are more accepting of slightly off-spec dtmf tones.

Peter