Page 56 of 910 Description
553-3001-365 Standard 4.00 August 2005
Gateway functional description
The Gateway performs the following functions:
• registers with the system using the TN Registration messages
• accepts commands from the system to connect/disconnect audio channel
• uses Realtime Transport Protocol/Realtime Conferencing Protocol
(RTP/RTCP) protocol to transport audio between the gateway and the IP
Phone
• encodes/decodes audio from PCM to and from the IP Phone’s format
• provides echo cancellation for the speaker on IP Phones for echoes
originating in the circuit-switched voice network (not applicable to the IP
Softphone 2050 or MVC 2050 as they have no handsfree capability)
Gateway functionality on the Meridian 1
Since there is no Signaling Server, each Voice Gateway Media Card
functions as both the LTPS and Voice Gateway.
The Gateway portion of the card connects to the Meridian 1 through the
DS-30X backplane. The Gateway portion also receives call speech-path setup
and codec selection commands through the ELAN network interface. The IP
Phone connects to both the Gateway and the LTPS functions through the
TLAN network interface.
Gateway functionality on the CS 1000 systems
A Signaling Server is always present in the CS 1000 systems. The LTPS
executes on the Signaling Server and the Voice Gateway executes on the
Voice Gateway Media Cards. The Voice Gateway Media Cards only provide
the voice gateway access.
Active Master
The LTPS maintains a count of the number of IP Phones registered to the
card. Each IP Telephony node has one active Master. The active Master
broadcasts to all Voice Gateway Media Cards and requests a response if it has
room for another IP Phone.