as you insert your pcmcia card into your computer , it give you this :
root@titatom:~# cardctl ident
Socket 0:
  product info: "Sony Ericsson", "GC85 PC Card", "ML2022"
  manfid: 0x0221, 0x2000
  function: 2 (serial)

root@titatom:~# cardctl info
PRODID_1="Sony Ericsson"
PRODID_2="GC85 PC Card"
PRODID_3="ML2022"
PRODID_4=""
MANFID=0221,2000
FUNCID=2


look at you're dmesg output, you should see a line like this one:
Jan 24 00:17:42 localhost cardmgr[4377]: + /dev/ttyS2:

here, our device is /dev/ttyS2, you must so replace it with you're in the first file. (on my debian/sid, udev link /dev/modem to it)

/etc/ppp/peers/caracas2
# This optionfile was generated by pppconfig 2.3.10.
#
#
debug
hide-password
noauth
connect "/usr/sbin/chat -v -t 180 -f /etc/chatscripts/caracas2"
debug
/dev/ttyS2
460800
defaultroute
noipdefault

user ''
password ''

usepeerdns
#novj
nobsdcomp
nodeflate
#With this option, pppd will accept all control characters from the peer, including those marked in the receive asyncmap
lcp-echo-failure 9999

# Use hardware flow control (i.e. RTS/CTS) to control the flow
# of data on the serial port.
crtscts

# Use the modem control lines.
modem

# Specifies that pppd should create a UUCP-style lock file for
# the serial device to ensure exclusive access to the device.
lock



/etc/chatscripts/caracas2
ABORT BUSY ABORT 'NO CARRIER' ABORT VOICE ABORT 'NO DIALTONE' ABORT 'NO DIAL TONE' ABORT 'NO ANSWER' ABORT DELAYED ABORT ERROR
'' AT
OK ATX3
OK AT+CFUN=1,1
OK 'AT+CPIN=0000'
OK AT&F
OK ATE0
OK ATV1
OK AT+CGMI
OK 'AT+CGDCONT=1,"IP","gprsweb.digitel.ve"'
OK "ATDT*99***1#"
CONNECT ''
# prelogin

'' \d\c
# end of pppconfig stuff


Now, you have to understand this:
This file send the pin number to the sim card, but it must be send only one time. So if you want to restart you're ppp connection, you'll need to comment out the line "OK 'AT+CPIN=0000'". And this is necessary, because, at least for me, the connection never come up at first try.

So, to start pppd, type:
pon caracas2


to stop it:
poff caracas2


But sometimes, it won't stop at first try to, so you'll have to poff it more than one time until you get an error.

sometimes, everyhing won't work anymore at all. So, you can do:
cardctl eject ; cardctl insert

next you have to uncomment the line with the pin number for the first "pon"
o