connect to 3G from command line (with pppd and chat)

3g

# file: /etc/ppp/peers/3g
# usage: pppd call 3g

connect '/etc/ppp/peers/dial -V -Upublicinternet -T*99***1#'

user internet
password internet

noauth
usepeerdns
noipdefault
defaultroute

nodetach
debug

dial

#! /usr/sbin/chat -f
# file: /etc/ppp/peers/dial
# save and make executable -- 'chmod +x /etc/ppp/peers/dial'
# Usage (in pppd config): 
# connect '/etc/ppp/peers/dial -V -U<APN> -T<dial number>'

ABORT "BUSY"
ABORT "RING"
ABORT "NO CARRIER"
ABORT "NO DIALTONE"
ABORT "ERROR"
ABORT "NO ANSWER"
REPORT CONNECT

# initialize
TIMEOUT  10
""       AT
OK       ATZ
OK       AT+CGDCONT=1,"IP","\U"

# dial
TIMEOUT  40
OK       'ATD\T'
CONNECT  \c

Make sure your sim card in the 3G modem doesn't require a pin -- alternatively add the pin to the dial file, something like AT+CPIN=1234