Timing synchronization information is communicated to a plurality of indoor communications devices supporting NB-IoT, e.g., indoor CBSDs supporting NB-IoT, from an outdoor communications device, e.g. a cellular base station supporting NB-IoT signaling using guard bands of a communications channel. An indoor device receiving the timing synchronization information from the outdoor device via NB-IoT signaling may, and sometimes does, process and forward synchronization information to other indoor devices, e.g. other CBSDs, which may be out of direct range of the outdoor device. In some embodiments, a plurality of outdoor base stations supporting NB-IoT receive timing reference information for distribution from the same NPT server coupled to a single reference source, e.g. an atomic clock.