title: Is APN login information stored on SIM cards?
body: <p>I am interfacing with a GSM modem module through the standard GSM AT command interface.  Right now the access point names (APN), user names, and passwords for each known carrier are hard coded in my software.  I am wondering if this information is provided by the carrier on the SIM card.  Is this the case?</p>
  
  <p>I am willing to try to directly access the file structure of the sim card with "+CRSM" or "+CSIM", but would like to know if the APN information is even there before I start.  If so, is there a link that describes SIM file structure that contains this information?  Many thanks.</p>