Dialing with kppp

It's more easier to dial with kppp, but there are still some problems because kppp was designed for a regular modem. So the AT commands are different (not all).
First we need to choose a modem device, it will be /dev/ttyI0 (your ISDN card. May be /dev/ttyI1,2,3 if you have more then one ISDN card).
Now we need to edit the modem commands. In the "Modem" tab there is a button named modem commands. It will let us change the modem commands.
Dial string = ATD
Answer string = ATA
Volume off = &E<Your phone number>
Volume low, high = Empty!!!

It's more easier to dial with kppp, but there are still some problems because kppp was designed for a regular modem. So the AT commands are different (not all).