How do I make a GPRS connection using the TCP/IP stack?

- Send: AT#GPRSMODE=1 (sets the modem to GPRS mode)
AT#APNSERV="APN" (sets the APN for the modem to connect)
AT+CGATT=1 (attaches the modem to the GPRS network)
AT+CGREG=1 (registers the modem onto the GPRS network)
AT#CONNECTIONSTART (to start the connection)
AT#CONNECTIONSTOP (to stop the connection)