A data collection network supports roaming terminals which may enter and exit a sleep mode to conserve power. A plurality of base stations each periodically transmit pending message indications to those roaming data collection terminals in range. Instead of requiring the transceiver within each terminal to always be active, the receiver is activated in synchrony with the transmissions of pending message indications from at least one of the base stations. Otherwise, the terminal may deactivate the transceiver, i.e., place it in a sleep state. The terminal may also sleep through pluralities of transmissions of pending message indications, and, thereafter, awake in synchrony to receive subsequent pending message indications. To minimize noise, the terminal may operate using a lower frequency system clock when not collecting data. When collecting data, especially where processing time proves more critical, the system clock frequency is increased.