Two Phases of P25?

We now know that there is an ASTRO P25 which works only for Motorola, and CAI (Common Air Interface) for everybody else trying to adhere to a common interoperability standard.  There are two types of systems - single site conventional and multi site (generally trunked, but not always).  Now we have another difference - Phase 1 versus Phase 2.

P25 Phase 1 provides one talk path per 12.5 kHz channel.  Phase 2 works very similar to DMR with 2 talks paths per channel.  In plain language, this means that two conversations can be taking place at the same time, privately without interference.  This is accomplished by splitting the channel into two separate 6.25 kHz "slots" (think "channels within a channel").  No P25 radio should be purchased today without a clear commitment from the manufacturers that the product is capable of meeting the final version of the Phase 2 standard and that the price for the upgrade will either be included at the time of purchase or available at a fixed guaranteed price when Phase 2 operation is practical.  Additional information on P25 is available by clicking here.