This applies for Saunalahti connection how I managed to make it work. At first it worked easily with pretty much with common settings but after update to Backfire 10.03.1-rc3 the problems began. Finally I managed to get it working by taking a peek to Ubuntu’s 3G options file and there it was in all simplicity. The following has worked so far, ppp options file is located at /etc/ppp:

nodetach
lock
defaultroute
noipdefault
noauth
usepeerdns
lcp-echo-failure 0
lcp-echo-interval 0
logfile /dev/null
debug
persist

The chat script in /etc/chatscripts/3g.chat. The one what I am using is basic. I only have one modem so I don’t need more versatility.

ABORT ‘BUSY’
ABORT ‘NO CARRIER’
ABORT ‘VOICE’
ABORT ‘NO DIALTONE’
ABORT ‘NO DIAL TONE’
ABORT ‘NO ANSWER’
ABORT ‘DELAYED’
REPORT CONNECT
TIMEOUT 6
‘OK-AT-OK’ ‘AT&F’
‘OK’ ‘ATE0V1X1&D2&C1S0=0′
‘OK’ ‘AT+CGDCONT=,,”$USE_APN”‘
SAY “Calling UMTS/GPRS”
‘OK’ ‘ATD*99#’
TIMEOUT 30
CONNECT ‘ ‘

Hope this helps if you have trouble with Saunalahti and a router with OpenWRT inside. Remember to install and check that you have all needed packages. Google will tell you. Cheers.