LMR Integration

 P25 ISSI (Inter RF Subsystem Interface) Media Gateway

The UnifyVoice P25 ISSI Media Gateway allows customers to interface the Tait P25 Radio Networks via ISSI. It performs interface functions between the UnifyVoice and P25 networks. This is a forward looking approach that offers a reduced cost of deployment and is not subject to near term obsolescence.
Other vendors approach PTToC integration by pushing P25 coded voice over the LTE network, terminating at the smart device. This approach, commonly referred to as “LTE25” is a costly model to deploy, in part due to the royalties associated with the P25 voice codecs at each device.
Meanwhile, Mission Critical PTT over Cellular (MCPTT) specifications are being established by 3GPP and are expected to be complete in 2016. The MCPTT features will be included in LTE Release 13 and do not currently include support for the LTE25 royalty bearing P25 codecs. As such any investment in expensive LTE25 will be short lived and soon obsolete.


The P25 ISSI Media Gateway offers a forward-looking approach with a reduced cost of deployment that is not subject to near term obsolescence.

Advantages of integrations using IP Media Gateways include:

  • Encrypted end-to-end communication between P25 Radio and LTE and WiFi Networks,
  • Significantly reduced cost of entry with software versus hardware centric analog gateway,
  • Additional feature transparency between the P25 and UnifyVoice users including User and Talk Group ID,
  • Emergency calls and more,
  • Forward compatibility with LTE Release 12 and Release 13, including Mission Critical PTT over Cellular,
  • Improved voice quality for all pure LTE communication on the network,
  • UnifyVoice users are homed on the P25 Network,
  • UnifyVoice Servers perform the subordinate media function.