Also known as: MPT 1327, MPT-1327, MPT1327
MPT 1327 is an analog trunked-radio signalling standard that originated in the United Kingdom. It uses a dedicated control channel carrying 1200 bit/s FFSK data to set up and manage analog FM voice channels, and it became one of the most widely adopted open trunking standards internationally.1 Because the signalling was published openly rather than tied to one manufacturer, MPT 1327 equipment was built by many vendors and deployed across dozens of countries.
Overview
MPT 1327 specifies the control-channel signalling — call requests, channel grants, short data messages, and unit/group identities — while the actual voice remains analog FM on the channels the control channel assigns. Signalling uses FFSK (fast frequency-shift keying, a form of audio FSK) at 1200 bit/s, chosen so it can pass through ordinary FM voice equipment. The standard is one of a family of related UK Ministry of Posts and Telecommunications (MPT) documents: MPT 1327 defines the signalling protocol, MPT 1343 the mobile numbering and registration scheme common in Europe, and MPT 1347 the radio interface requirements. Identities are structured as prefix, fleet, and unit numbers, and the system supports group calls, individual calls, status messages, and short data. Its openness made it the natural choice for operators who wanted trunking without committing to a single vendor’s ecosystem.
Technical characteristics
| Property | Value |
|---|---|
| Access | FDMA with a dedicated control channel |
| Control signalling | 1200 bit/s FFSK |
| Voice | Analog FM |
| Identities | Prefix / fleet / unit numbering (MPT 1343) |
| Related specs | MPT 1327 (signalling), MPT 1343 (numbering), MPT 1347 (radio interface) |
| Services | Group/individual calls, status, short data |
History
MPT 1327 was published in the UK in the 1980s by the then British telecommunications regulator as an open specification for trunked private mobile radio.12 It filled the role that proprietary systems like Motorola Type II and EDACS played elsewhere, but with a multi-vendor, standards-based approach. Widespread adoption followed across Europe and beyond, and the MPT family remained the dominant open analog trunking standard until digital systems such as DMR and TETRA arrived.
Deployment
MPT 1327 saw heavy use in business, transport, and government fleets across Europe, Asia, Africa, Australasia, and South America — taxi networks, utilities, and national operators among them. It is now declining as digital standards take over, but a substantial installed base persists, especially in regions where the systems remain cost-effective for existing users.
Decoding it with GopherTrunk
Following an MPT 1327 system means demodulating the 1200 bit/s FFSK control channel, decoding its address and grant messages, and steering the receiver to the assigned analog FM voice channel — the standard control-channel trunk-tracking workflow. Because voice is plain FM, no vocoder is involved. See the Status page for GopherTrunk’s current MPT 1327 control-channel support.