Configure GPRS module

I'm developing a project that aims to get the location of the GPS and send via GPRS to the server. But I want to know how to configure the APN so that it can be accepted chip from any operator in the GPRS module?

 while ( start_GPS() == 0);

while (sendATcommand("AT+CREG?", "+CREG: 0,1", 2000) == 0);

// sets APN , user name and password
sendATcommand("AT+SAPBR=3,1,\"Contype\",\"GPRS\"", "OK", 2000);
sendATcommand("AT+SAPBR=3,1,\"APN\",\"*******\"", "OK", 2000);
sendATcommand("AT+SAPBR=3,1,\"USER\",\"*******\"", "OK", 2000);
sendATcommand("AT+SAPBR=3,1,\"PWD\",\"*******\"", "OK", 2000);

// gets the GPRS bearer
while (sendATcommand("AT+SAPBR=1,1", "OK", 20000) == 0)
{
    delay(5000);
}

delay(1000);
while(Serial.available() != 0)
{
  Serial.read();  
}