Abstract: A system for providing error-free data communication between first and second personal computers over a conventional cellular telephone system includes an interface adapter coupling the first personal computer to the TDATA, CDATA, and RDATA conductors of a Cellular Subscriber Equipment unit and a cellular connector coupling a modem of the first personal computer to the audio R.sub.x and T.sub.x conductors of the Cellular Subscriber Equipment unit. Data communication between the first and second personal computers is carried over the voice channel of the cellular telephone system. The interface adapter recognizes imminent interfering activity such as a handoff or power adjustment operation or multipath fading by monitoring the TDATA, CDATA, and RDATA conductors of the control channel of the cellular telephone system and so informs the first personal computer.