What is a Cross-Network Gateway?
--It enables voice communications among the Radio, VoIP, and Public Announce (PA) networks.
--It incorporates Radio over Internet Protocol (RoIP) which converts radio voice communications into VoIP.
--It links up various radio networks together in order to extend the geographical coverage.
--It is a GSM voice gateway by enabling voice communications to and from the telephone networks (GSM and PSTN)
--It enables a voice connection to the public announce system for general and emergency broadcast.
--It makes recording of voice communications among various networks simple and easy.

Who needs a Cross-Network Gateway?
--Adio Service Operators who would like to expands their geographical coverage.
--Radio User who would like to make and receive calls from the telephone networks.
--System administrators who would like to monitor and maintain good control over the existing radio networks.
--System Integrator who would like to build or deploy a reliable voice communication network in timely manner

Overview
   The fundamental of RoIP(Radio over IP)technology is to convert the audio and PTT signals in a radio terminal into IP packets and then transmit the data via the IP networks. The challenge in this technology is to insure that the audio is transmitted in real time and the PPT control signal is transmitted immediately and reliably. The radio range is general limited by the restricted transmitting power, the antenna sensitivity, and other environmental factors.

Key Features
--Open Standard VoIP Protocols (IETF SIP V2)
--Two 10/100 Ethernet for WAN / LAN connections
--Supply dynamic DNS service
--Speech quality ensured by QoS at the Ethernet and IP layers and comprehensive jitter buffer
--Line Echo Cancellation
--VLAN and QoS support
--NAT Transversal and Router functions
--Support IP voice stream to via a recording server
--Highly stable embedded Linux operating system in high performance ARM 9 Processor
 
Basic Features
--Two RJ-11 FXS port for traditional phone set or PBX's trunk line
--Support three PTT port
--LEDs for Power, Ready, Status, WAN, PC, FXS
--Call Forward, Call Hold, Call Transfer
--Dial Plan
--Caller ID
 

Enhanced Features

--Dynamic selection of codec
--Advanced jitter buffer
--Automatic traversal of NAT and firewall
--VLAN / Qos
--Router
--Echo cancellation for Speakerphone
--Comfort noise generation (CNG)
--Voice activity detection (VAD)
--Auto provisioning (requires auto provisioning server)
--On line firmware upgrade
--Multi-language support: English and Chinese
 

Supported Standards

--ITU: H.323 V4, H.225, H.235, H.245, H.450
--RFC 1889 - RTP/RTCP
--RFC 2327 – SDP
--RFC 2833 – RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals
--RFC 2976 – SIP INFO Method
--RFC 3261 – SIP
--RFC 3264 – Offer/Answer model with SDP
--RFC 3515 – SIP REFER Method
--RFC 3842 – A Message Summary and Message Waiting Indicator
--RFC 3489 – Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NATs)
--RFC 3891 – SIP “Replaces” Header
--RFC 3892 – SIP Referred-By Mechanism
--draft-ietf-sipping-cc-transfer-04 –  Session Initiation Protocol Call Control - Transfer
--Codec: G.711 (A/µ law), G.729A/B, G.723.1
--DTMF: RFC 2833, In-band DTMF, SIP INFO

Applications
   Extending Service Coverage
   Radio service coverage is often affected by the geographical landscape, like high hills. The traditional method is to build expensive radio repeaters on the hills in order to extend the radio service coverage. In addition, its maintenance cost is high and its performance is affected by the weather. In this case, the Xtrunk gateways are the perfect solution. They are low cost and easy to install and maintain. They offer a very stable and reliable link between the two sites.

If you have any doubt or want to know further information,please feel free to contact me.