getMobileInfo: function() {
    LOG("updateMobileInfo called");
    try {
      let radioService = Cc["@mozilla.org/ril;1"]
                    .getService(Ci.nsIRadioInterfaceLayer);
      let numInterfaces = radioService.numRadioInterfaces;
      let result = [];
      for (var i = 0; i < numInterfaces && i < 10 /*safeguard*/; i++) {
        LOG("Looking for SIM in slot:" + i + " of " + numInterfaces);
        let radio = radioService.getRadioInterface(i);
        let iccInfo = radio.rilContext.iccInfo;
        let cell = radio.rilContext.voice.cell;

        if (iccInfo && cell) {
          // TODO type and signal strength
          result.push({ radio: "gsm",
                      mobileCountryCode: iccInfo.mcc, 
                      mobileNetworkCode: iccInfo.mnc,
                      locationAreaCode: cell.gsmLocationAreaCode,
                      cellId: cell.gsmCellId });
        }
      }
    
      return result;
    } catch(e) {}
    return null;
  },