In the TC45, we simply do this :
// Setup Gprs
String response;
response = ata.send("AT^SJNET=GPRS," + gprsPoint + "," + gprsUser + "," + gprsPass + "\r");
if (response.indexOf("OK") >= 0)
{
System.out.println("GPRS Setup : OK " + gprsPoint);
}
Easy!