Yep ive seen pnatd but im not sure what at commands it accepts and dont know what tty it would use ?Would appreciate more info though...me and modems is not something im hugely experianced in yet
Nokia-N900:~# pnatd -p /dev/pts/2
Nokia-N900:~# ln -s /dev/pts/2 /dev/modem
Nokia-N900:~# screen /dev/modem AT OK ATDT100; OK <number is dialed>