This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
mcc is a read-only property representing the Mobile Country Code (MCC) of the subscriber's home network.
var mcc = navigator.mozMobileConnection.iccInfo.mcc;
Return a number.
Not part of any specification.