A mobile vehicle communications system and a method of sending one or more secure short message service (SMS) messages using that system. The method includes the steps of: (a) determining at a sender a data quantity associated with zero or more proprietary data parcels (PDPs) to send within one or more SMS messages; (b) configuring an encrypted payload of each of the one or more configured SMS messages to carry the total number of PDPs, wherein when the size of the payload would result in an SMS message exceeding 140 bytes, the configuring step includes configuring a plurality of SMS messages to carry the payload; and (c) transmitting from the mobile originated device one or more configured SMS messages.