Sec.  22.623   System configuration.

   This  section requires a minimum configuration for point-to-multipoint
   systems using the channels listed in  Sec. 22.621.

   (a) 928–960 MHz. The channels may be assigned, individually or paired, only
   to fixed transmitters in a system that controls at least four public mobile
   base  transmitters that transmit on the same channel. If a 932–933 MHz
   channel and a 941–942 MHz channel are assigned as a pair, the 941–942 MHz
   channel must be assigned only to control transmitters; the 932–933 MHz
   channel may be assigned to control or fixed relay transmitters.

   (b)  470–512  MHz.  These  channels  may be assigned only individually
   (unpaired), to control transmitters that directly control at least four
   public mobile base transmitters that transmit on the same channel. Fixed
   relay transmitters are not authorized.

   (c) Selection and assignment. The FCC selects and assigns a channel when
   granting applications for authorization to operate a new station to transmit
   in the 470–512, 932–933 and 941–942 MHz frequency ranges. Applicants having
   a preference may request the assignment of a specific channel or channel
   pair, but the FCC may in some cases be unable to satisfy such requests.