/dev/ed0
device!
If all else fails, send as much information as you can, including your config files, how you're starting ppp, the relevant parts of your log file and the output of the netstat -rn command (before and after connecting) to the freebsd-questions@FreeBSD.org mailing list or the comp.unix.bsd.freebsd.misc news group, and someone should point you in the right direction.
/dev/ed0
device!