On-the-air interception *is* too labor intensive, relatively speaking, given that a cellular call originating or terminating at a given switch can pass through a number of individual cells, each of which would need to be monitored. However, that does not negate the potential usefulness of on-air interception as an *intelligence-gathering* tool from which the results can be fed into the process of getting a warrant to tap at the switch. The problem of maintaining privacy can be and in fact *is* effectively solved though. A couple of companies are making cellular to 2500-set adapters which basically allow any regular single-line device to be plugged in and transmit via cellular. This obviously includes standard modems, plus or minus the problems associated with variable transmission quality over the airwaves. So any regular cryptosystem that can work on analog lines should be applicable here. If anyone out there is further interested in these cellular-to-single-line-device adaptors, email me and I can get prices and specifications. -gg