Cisco IP Interoperability and Collaboration System

Cisco ISSI Gateway

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The Cisco ® IP Interoperability and Collaboration System (IPICS) solution now has a direct IP connection to Project 25 (P25) radio networks using standard TCP/IP communications. Cisco IPICS also connects smart devices such as the Apple iPhone ® with mission-critical users on the same P25 radio network. The Cisco Inter-RF Subsystem Interface (ISSI) Gateway provides communications interoperability, regardless of technology and jurisdiction boundaries.
The Cisco ISSI Gateway uses TCP/IP standardized communications to bridge P25 networks to Cisco IPICS. The Cisco ISSI Gateway connects to the first open IP radio network standard. Customers no longer have to be locked into a proprietary interface between their communications dispatch system and the radio network. The Cisco ISSI Gateway is based on the Inter-RF Subsystem interface (ISSI) standard, issued by the Telecommunications Industry Association (TIA) as the TIA-102.BACA specification.
The Cisco ISSI Gateway can be deployed on the Cisco Physical Security Multiservices Platform or virtualized on the Cisco Unified Computing System , which represents the start of a new generation of virtualized appliances for use with the Cisco IPICS product line.

Figure 1. Cisco ISSI Gateway on 2-RU Cisco Physical Security Multiservices Platform

Figure 2. Cisco Unified Computing System for Virtualized ISSI Gateway

Product Specifications

Table 1 describes some of the features of the Cisco ISSI Gateway,

Table 1. Cisco ISSI Gateway Features and Descriptions



Standard network-level communications

Provides TIA standard network-level communications between P25 trunking radio systems, regardless of radio system manufacturer

Authorized roaming

Allows authorized roaming between P25 systems

Radio controller

Coordinates calls and traffic from a common database of all subscribers in the system

Radio signaling

Users can communicate using P25 supplemental services, including:

• Group Calls
• Individual Calls
• Emergency Calls
• Call Alert
• Radio Check
• Radio Detach
• Radio Inhibit/Uninhibit
• Radio Unit Monitor
• Short Message
• Status Query

Secure Communications

Encrypts and decrypts P25 audio in two different modes. Gateway P25 mode allows for system-level encryption coming from G.711/G.729 audio streams, and End to End P25 mode allows for end-to-end encryption from radios to the dispatchers without transcoding.

The Cisco ISSI Gateway comprises two functional parts: a radio controller and a subsystem interface. The radio controller manages P25 subscribers, allowing for the administration of user and group IDs for the home and affiliated radio system. This ensures talkgroup communications while radio users roam away from their home P25 network onto an affiliated P25 network without a console patch. The Console Subsystem Interface (CSSI) allows the IPICS dispatch console, Cisco IP Phones, and Cisco mobile clients on Apple iPhone phones to communicate with multiple P25 systems. Customers are no longer tied to a radio manufacturer's proprietary dispatch solution or proprietary mobile or portable radios.


The Cisco ISSI Gateway comprises the following functional building blocks (see Figure 3).

• Radio Controller Interface

• IMBE Vocoding

• Gateway P25 talkgroup encryption/decryption

• P25 talkgroup affiliations

• P25 Radio signaling

Figure 3. Cisco ISSI Gateway functional diagram

Cisco's P25 solution allows for two modes of communications. Gateway P25 is a proxy mode that encodes/encrypts and decodes/decrypts P25 audio on the ISSI Gateway. In this mode, the ISSI Gateway transcodes multicast Real-Time Transport Protocol (RTP) streams using G.711 into Session Initiation Protocol (SIP), using IMBE, sending the streams throughout the IP network. Gateway P25 mode allows IP phones, mobile clients, and other SIP endpoints to talk with P25 radios. End to End P25 is a native mode that allows for end-to-end encryption of audio using IMBE. In End to End P25 mode, the ISSI Gateway routes the audio directly to the IPICS dispatch console, where it encodes/encrypts and decodes/decrypts the P25 audio.

Software System Capabilities

Table 2 describes some of the software features of the Cisco ISSI Gateway.

Table 2. Cisco ISSI Gateway Software Features

Maximum simultaneous P25 group calls


Maximum concurrent End to End P25 talkgroups


Maximum P25 talkgroups per ISSI Gateway



256-bit AES & 64-bit DES-OFB: contact Cisco for other encryption formats

Hardware Specifications and Hardware Part Numbers

See Cisco Multiservices Platform and Unified Computing System products.
Table 3 lists ordering information for this solution,

Table 3. Ordering Information

Part Number



IPICS P25 ISSI Gateway; includes (4)CIS-P25-TG licenses. Order as option to 2-RU MSP or as an option to the CIS-IPICS-VM.


IPICS P25 talkgroup; order one for each talkgroup in the ISSI Gateway.


IPICS dispatch console P25 dispatcher license; order one IPICS native license for each dispatcher that needs end-to-end secure communications.


Order this for a Virtualized version of the ISSI Gateway and structure all previous software as options to this part number.

Services and Support

Cisco and our certified partners can help you accelerate success and improve the return on your investment in a Cisco IPICS solution. The Cisco lifecycle approach to services defines the requisite activities at each phase of the solution lifecycle:

• Reduce deployment costs by identifying the features that will best meet your business requirements

• Accelerate migration by assessing the readiness of your network to support the system and by developing a sound design

• Support smooth implementation through effective planning and expert installation, configuration, and integration

• Increase operational efficiency and extend the value of your investment with award-winning technical support

For more information about Cisco services, visit

For More Information

For more information about Cisco IPICS, visit or contact your local account representative.
For more information about APCO Project 25, visit