Cisco Cisco IOS XE 3.13S
Revised: December 21, 2015,
LMR over IP Overview
A Land Mobile Radio (LMR) system is a collection of portable and stationary radio units designed to communicate with each other
over predefined frequencies. They are deployed wherever organizations need to have instant communication between geographically
dispersed and mobile personnel. Typical LMR system users include public safety organizations such as police departments, fire
departments, and medical personnel. However, LMR systems also find use in the private sector for activities like construction,
building maintenance, and site security.
over predefined frequencies. They are deployed wherever organizations need to have instant communication between geographically
dispersed and mobile personnel. Typical LMR system users include public safety organizations such as police departments, fire
departments, and medical personnel. However, LMR systems also find use in the private sector for activities like construction,
building maintenance, and site security.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see
and the release notes for your platform and software release. To find information about the features documented in
this module, and to see a list of the releases in which each feature is supported, see the feature information table.
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Information About Land Mobile Radio
In typical LMR systems, a central dispatch console or base station controls communications to the disparate handheld or mobile units
in the field. The systems might also employ repeaters to extend the range of communications for the mobile users. LMR systems can
be as simple as two handheld units communicating between themselves and a base station over preset channels. Or, they can be quite
complex, consisting of hundreds of remote units, multiple dispatch consoles, dynamic channel allocation, and other elements.
in the field. The systems might also employ repeaters to extend the range of communications for the mobile users. LMR systems can
be as simple as two handheld units communicating between themselves and a base station over preset channels. Or, they can be quite
complex, consisting of hundreds of remote units, multiple dispatch consoles, dynamic channel allocation, and other elements.
LMR over IP Service
With the LMR over IP service, standards-based VoIP technology voice gateways are used in combination with additional LMR
specific features to address interoperability, extending command and control, and other issues. Base stations, repeaters, and dispatch
consoles generally possess a wired interface that can be used to monitor audio received from their air interface, and as input for audio
to be transmitted on their air interface. Although this wired interface may contain other control capabilities as well, as long as it has
some sort of speaker output and microphone input, it can be connected to a voice port on a router.
specific features to address interoperability, extending command and control, and other issues. Base stations, repeaters, and dispatch
consoles generally possess a wired interface that can be used to monitor audio received from their air interface, and as input for audio
to be transmitted on their air interface. Although this wired interface may contain other control capabilities as well, as long as it has
some sort of speaker output and microphone input, it can be connected to a voice port on a router.
The audio received on the voice port is encoded with a standard audio codec, such as G.711 or G.729. Those audio samples are
packaged in standards-based Real-Time Transport Protocol (RTP) packets suitable for transport on an IP network. At this point, the
communication element is abstracted from the distinctive characteristics of each radio system, thus providing a solution for the
interoperability problem. Now, these audio packets can be sent across the network to other LMR gateways with different brands of
radio systems either individually (unicast) or as a group (multicast).
packaged in standards-based Real-Time Transport Protocol (RTP) packets suitable for transport on an IP network. At this point, the
communication element is abstracted from the distinctive characteristics of each radio system, thus providing a solution for the
interoperability problem. Now, these audio packets can be sent across the network to other LMR gateways with different brands of
radio systems either individually (unicast) or as a group (multicast).
The recipient of the audio packets need not be another LMR gateway. It can be any device capable of receiving and decoding the
RTP stream, such as an IP telephone or PC with appropriate software. The IP network and IP-enabled devices can be used to allow
users to monitor or transmit on a particular radio channel from a desk without issuing another radio. This can be done locally,
nationally, or internationally, assuming the IP network has been properly designed.
RTP stream, such as an IP telephone or PC with appropriate software. The IP network and IP-enabled devices can be used to allow
users to monitor or transmit on a particular radio channel from a desk without issuing another radio. This can be done locally,
nationally, or internationally, assuming the IP network has been properly designed.
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