In an exemplary embodiment, a test pattern is sent by a base station at a suitable point in a communications protocol. According to the evaluation of the test pattern transmission, a relatively high data rate or a lower more conservative data rate is selected for the transmission of a relatively lengthy data message. In the most general case, the test pattern can comprise a query from a mobile unit having a message to send, and such test pattern can be transmitted at the lower data rate where its transmission characteristics (e.g. signal strength, jitter or quality of transmission of known information) can be used to predict probable feasibility of transmission at the higher data rate.