Contact at 305.500.9302
Serving the telecom industry since 2001

Protocol MPT1327



Radio spectrum throughout the world is becoming congested. Making use of a MPT1327 trunking system allows you to keep number of radio bands to an optimum minimum.

More users need to be given access to the same number of channels: trunking gives you efficient and automatic channel sharing.

Users are demanding a wider geographical area of use than is economically viable with most conventional radio systems. MPT1327 trunking systems can be organized in wide-area switched networks.

Availability of a digital control channel makes it possible to implement a number of custom radio dispatch applications such as dynamic regrouping, messaging, paging, GPS, remote-controlled alarm systems, telemetry, etc.


Protocol MPT1327 is a family of standards which defines a trunking system for Private Mobile Radio (PMR).

A conventional PMR service offers the user a single channel. When the user wishes to make a call, this channel may well be occupied by another user. The prospective user must wait until the end of the conversation and then compete with others to obtain the vacant channel.

In a trunking system, a set of channels shares the communication demands of the users. If no channel is free at the time a user makes a call, the call will be placed on hold for a few seconds until any channel becomes available. As a result, the user has less time to wait and enjoys a better quality of service.


Trunking was developed because radio spectrum throughout the world is becoming congested. Dynamic growth in mobile communications has made channel availability very difficult and the increasing consumer demand for the benefits of mobile communications means that more and more users need to be given access to the same number of channels, without any loss of quality of service.

At the same time, users are demanding a wider geographical area of use than is economically viable with most conventional PMR radio systems.

Advances in technology have allowed trunking techniques, previously only associated with hard wire communications, to be applied to radio networks. These allow more efficient use of spectrum.

The time is right for trunking and Protocol 1327.


Each radio station transmits a control signal on a radio channel. It also has a number of "traffic" channels at its disposal on which users of radio units communicate. When not in use, the radio unit is automatically tuned to the control signal and the unit's microprocessor can communicate with the system computer on this channel at any time.

When the user wishes to make a call, the unit transmits the request in the form of a data signal to the system computer. the computer finds the caller's desired correspondent and, by means of the control channel, checks for willingness to receive a call. When both called and calling parties are ready to communicate, the computer allocates the first available "traffic" channel.

When the call is terminated by either party, the radio unit sends a data signal releasing the channel.

Radio stations may be interconnected to increase the service area to provide any size of network, up to a national or international level.

Calls may also be made into other fixed line networks such as telephone systems.


In the early 1980s, leading telecommunications manufacturers pioneered work on Protocol 1327 under the auspices of the UK Department of Trade and Industry.

MPT1327 was developed over a two-year period and was the first of the Protocol 1327 family of standards. This is the signaling standard and is incorporated into UK trunked radio networks as the basic operating system.

To arrive at the optimum working implementation of the MPT1327 standard, network operators were consulted and the following additional standards were developed:

MPT1343 - defining the behavior of radio units on public networks

MPT1347 - the fixed network specification to complement MPT1343

MPT1352- the test schedule which radio units pass before being accepted on to radio networks.


The development of Protocol 1327, which provides the heart of these trunked mobile radio systems, has led to an immediate improvement in the grade of service and, moreover, has allowed a large increase in traffic capacity compared with single-channel, non-trunked systems.

Wide area networks have been set up throughout the UK for users of shared systems in the Band III frequencies and cover much of mainland Britain. Two national networks have been established, and several companies have been licensed to set up and operate local single-and multiple-site systems. They offer operators of commercial vehicle fleets a communications system which has major benefits over private mobile radio technology.

The networks provide excellent clarity and call security. Users can make rapid, dedicated voice and data communications to other units, and have the ability to connect to their company's private telephone system and main computer; dialing into the public switched telephone network is also possible.

Leading electronics manufacturers worldwide have developed radio units especially to meet the Protocol 1327 standards. They provide a choice of features such as handsets of fist microphones, a range of dialing facilities and hands-free operation to enable safe communications on the move.

Tens of thousands of users are already operating on the new networks. Among those benefiting are a number of UK organizations ranging from local small businesses to the large public utility companies which prefer to operate their own closed system.

With a need to stay in constant communication with a large number of service vehicles over a wide area, the use of Protocol 1327 is allowing better vehicle use, greater manpower efficiencies and significant operating economies.


Protocol 1327 is proven technology. the UK experience is evidence of the success of these standards. Their widespread adoption will provide great opportunities for manufacturers by establishing a worldwide market for their products.

Systems can be set up quickly since network and user systems already exist. There need be no troublesome delays while standards are devised and equipment is designed and produced. Systems can be set up immediately whilst home manufacturers develop their own products.

Because the Protocol 1327 standards are flexible, they can be easily implemented to suit specific requirements. When universally adopted, the transfer of radio units conforming to similar frequencies between networks and countries will no longer be a problem.

Of course, users will benefit too. the larger the market and economies of scale, the less expensive the subscriber equipment.


Two-way conversation with a variety of types of call.

Data transmission


Conference calls.
Call transfer Available.