This value reports (and may be set for override purposes) the Mobile Network Code (MNC), with -1 meaning "Not Applicable," which together with the MCC uniquely identifies the specific carrier network. An admin uses this alongside c3gGsmMcc to precisely and programmatically identify the exact carrier network the modem is attached to, useful for automated cross-checking against an expected home-network value. For example, comparing the MCC/MNC pair against a known list of home-carrier codes lets an admin's monitoring system automatically flag devices that have roamed onto a different carrier.