From The RadioReference Wiki
Revision as of 00:21, 8 December 2013 by QDP2012 (updated link after linked-page was renamed)
ProVoice is MA/Com's (formerly Ericsson) implementation of IMBE digital modulation for radio communications. It is not APCO-25 compliant, but does use the same IMBE vocoder developed by DVSI Inc. The technical difference between ProVoice and the APCO Project-25 standard is how error correction and modulation is provided to transmit the data.
There is also an older type of digital communications for EDACS Systems, which goes by the trade name AEGIS.
San Antonio, Texas, and the State of Florida are using or are in the process of building ProVoice EDACS systems with ESK. Cecil County, Maryland utilizes a VHF Pro-Voice system which does not use ESK, but rather a different format of EDACS where any analog transmissions can't be monitored by any commercial scanner.
EDACS ProVoice systems use the MA/Com EDACS control channel.
There is no scanner available today that can monitor EDACS ProVoice Digital voice by itself but it can be monitored with DSD.