The common POCSAG paging standard is being supplanted by a new,
four-level signaling protocol called FLEX, marketed and licensed
by Motorola.
An interesting FLEX decoding project used to be
here,
but has disappeared. Some additional information might be found
here, although
even he appears to have disappeared.
The GNUradio folks are using a Microtune 49X7 cable modem tuner
(part of Microtune's 4937 DI5 RF tuner module series)
with a 5.75 MHz IF and Measurement Computing PCI DAS4020/12
12-bit 20 MSPS A/D card to do some interesting software
defined radio (SDR) work.