phillip, it seems that we have somehow the same problem, but we have an additional strange behavior. we used wireshark on the incoming network-card and on the outgoing side. there we see two strange things, we can not figure out: 1.) on the incoming side, we receive the in-band tone from the cirpack with a tiny gap, but fs recognizes them as 2 tones. in wireshark it look something like this: | |||||||| as i said, fs sees this as two tones. 2.) fs sends the tone above to the outgoing side as two tones, but seems to cut the first ms of the second part. in wireshark it looks something like this: | ||| i feel, that we have to find out the following: 1.) why does the tone already have a gap, when we receive it? 2.) why does fs not leave the tone untouched? something happens with the tone, while passing fs. is there a setting to avoid this? 3.) why is there no easy way to completely delete dtmf tones, if it is possible with vuvuzela-noise? ;-) dennis