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Introduction
Packet Voice Processor Commands Manual
In this example, SIP signaling occurs as described in
below.
Table 1-1 Call Initiation - Enterprise End-to-End Application
Step Description
1
An employee within the Enterprise IP Network starts the call by going off-hook or dialing a
number on an IP phone. This sends a SIP INVITE request to the IP PBX via a logical connection.
The network path for this signal is though the enterprise LAN or WAN.
Note: The solid lines in
represent the SIP signaling path. The dotted lines
represent the RTP media path.
2
The IP PBX soft-switch determines the destination of the call from the collected digits. If the call
is within the LAN, the call is routed internally and no signaling to the IXC IP Network takes place.
Otherwise, the IP PBX sends a SIP INVITE request to a designated proxy server (SIP Proxy 1).
3
The session border controller receives the INVITE and forwards it to SIP Proxy 1 within the IXC
IP network.
4
SIP Proxy 1 is configured to send the SIP INVITE Request to an available Packet Voice
Processor for subsequent media voice quality processing. SIP Proxy 1 forwards the request to
the Packet Voice Processor SIP agent.
5
The Packet Voice Processor receives the SIP INVITE, prepares the media path and forwards the
INVITE to the SIP server (SIP Proxy 2) in the network that controls the routing of the call to its
end destination (PSTN).
6
The Packet Voice Processor acts as a termination point for the SIP signal and re-generates the
INVITE towards SIP Proxy 2.
7
The Packet Voice Processor negotiates the session description with the MTA or IP phone to
determine the codec type and the requirements for transcoding.
Note: Voice quality enhancement (using VQA and IPR technologies) will also be applied to the
media based on the Packet Voice Processor’s configuration.
8
SIP Proxy 2 determines that the destination of the call is on the PSTN. It then terminates the SIP
connection and issues an H.248 command to the media gateway within the IXC IP network,
indicating that there should be an RTP connection from it to the Packet Voice Processor.
Note: The solid lines in
represent the SIP signaling path. The dotted lines
represent the media path.
9
The media gateway establishes the connection to the Packet Voice Processor.
10
The signal path is reversed and all of the preceding SIP proxies receive an OK.
11
The IP Phone starts the RTP voice transmission.
12
The voice path follows from the IP Phone through the enterprise LAN network, through the
Enterprise IP network to the session border controller, and into the Packet Voice Processor.
13
The Packet Voice Processor transcodes the media path, applies voice quality enhancement, and
forwards the traffic to the media gateway.
14
From the media gateway, the media is passed to the PSTN network and the called party.
