this is how to use your cell phone for internet access. ive only tried
on linux with tmobile. (motorola v300 and v360) but it should work on 
bsd. for os x see http://www.taniwha.org.uk/

check with 611 for the exact dial string etc, then make these two files, 

-- pppdscript.sh --
#!/bin/sh

DEV=/dev/ttyACM0
SPEED=230400
CHATSCRIPT=/etc/chatscripts/tmobile

OPTS="$OPTS noauth"
OPTS="$OPTS usepeerdns"
OPTS="$OPTS defaultroute"       
OPTS="$OPTS noipdefault"
OPTS="$OPTS crtscts"            
OPTS="$OPTS idle 300"

/usr/sbin/pppd connect "/usr/sbin/chat -v -f $CHATSCRIPT" $DEV $SPEED $OPTS

-- chatscript --

ABORT ERROR
'' ATZ
OK AT+cgdcont=1,"IP","internet2.voicestream.com"
OK ATD*99#
CONNECT ''

when you use noauth, pppd wants to only be run as root. you can use sudo, but setuid wont work.