I have the same problem and wanted to try 2 stop bits... but how do you do set it up?
This is the problem that I have...
At the CPU I use "pon"; hence the connection is controlled via a ppp options file in /etc/ppp/peers/ and a chat script in /etc/chatscripts/.
So I need to tell the cpu and the modem to use 2 stop bits...
I cannot find an option to do this in the ppp options file.
- if I use an "stty" with cstopb set, prior to starting the link, it gets reset when ppp starts up.
- putting cstopb in the ppp options file just generates an error.
I cannot find a modem AT command to put in the chat script to switch the modem to 2 stop bits.

Can anyone offer any suggestions?