Abstract: Systems and methods are disclosed for layered, secure data communications with a mobile unit over a variety of different communication links, such as in-band signalling, SMS, CDPD etc. A privilege control table determines permitted classes of messages. Content labeling is used to further manage communications without reading the payload of the message. The invention adds additional layers of security by varying content labels based on secure session key exchange seeded algorithms. The system also includes isolating the application program by providing a protocol manager for exclusive receipt of a communication service request from the application program; the protocol manager implementing a plurality of different message protocols. Another aspect of the invention includes link choose logic for effecting loosely-coupled, network loop communications to enable broadband delivery to a mobile unit, and can include parallel transmission of segmented messages over plural communication links.