The actions are mapped to  3 ~4 AT command, and one PPP process.

 

1. Request GSM

    AT+CREG.

2. Attached to GPRS network

    AT+CGATT

    AT+CGDCONT

3. PPP process after *99***1#

 

Our module control is very simple: AT commands. The following commands flow are applicable to the MC55, MC56 and SIMCOM's SIM300.

Some recorded AT commands flows are...
from China Mobile's SIM card (in H50+ MC55(?)) generated AT-log in Shanghai, captured on 
Sat morning 1am+ at 19 Jun 2010:
--------
AT :　    [Start-up confirmation that module will response AT command]
ATE0V1 ： [disable echo, detailed responses on]
AT\Q3                     [RTS/CTS hardware handshake on]
at+csq                    [Signal quality]
at+creg?                  [Network registration]
AT+CIMI                   [Request International Mobile Subscriber Identity (IMSI)]
AT+GSN                    [request International Mobile Equipment Identity (IMEI)]
at+cgatt=1                [attach the terminal to GPRS service]
at+cgatt?                 [Return the current GPRS service state]
at+cgdcont=1,"IP","cmnet" [Define PDP Context]
at+csq                    [Signal quality]
atd*99***1#               [Request GPRS service]