Mandatory

Analog FM used in 25 kHz and 12.5 kHz bandwidths is mandatory in all P25 Phase 1 subscriber equipment — hand-held (portable) and vehicular (mobile) transceivers — to provide compatibility with non-P25 systems. (Digital Modulation and Spectrum Efficiency Two-Phase Plan describes Phase 1.)

Analog FM Transceivers lists the documents associated with this P25 equipment feature. The analog FM air interface is not a part of the P25 Standard, but tests are specified for analog FM transceiver performance.