Linksys SPA9000 Administration Guide

Linksys Voice System Administration Guide 130
A
Technology Background
Advanced Topics in LVS Administration
This appendix provides technical information that is useful to individuals who want a better
understanding of how the LVS works.
• ”Technology Background,” on page 130
• ”SPA9000 Architecture,” on page 134
• ”SIP-NAT Interoperation,” on page 135
• ”Advanced Call Control and Routing,” on page 137
• ”Configuring Vertical (Supplementary) Service Codes,” on page 137
• ”Advanced Topics for SPA400 Voice Mail Service,” on page 141
• ”Remote Provisioning Features,” on page 145
Technology Background
This section provides background information about the technology and protocols used by the
SPA9000 system. It includes the following topics:
• ”Session Initiation Protocol,” on page 130
• ”SPA9000 Media Proxy,” on page 132
• ”Using the SPA9000 with a Firewall or Router,” on page 133
• ”SPA400 SIP-PSTN Gateway,” on page 133
Session Initiation Protocol
The LVS is implemented using open standards, such as Session Initiation Protocol (SIP),
allowing interoperation with all ITSPs supporting SIP. Figure A-1 illustrates a SIP request for
connection to another subscriber in the network. In the SIP protocol, the requestor of the
session is called the user agent server (UAS), while the receiver of the request is called the user
agent client (UAC).

Linksys SPA9000 Specifications

Physical Interfaces

Ethernet ports	2 10/100BaseT RJ-45
Phone ports	2 RJ-11 FXS
Ring voltage	40-55 VRMS
Ring frequency	10 Hz - 40 Hz
Maximum ringer load	3 REN

Power

On-hook voltage	-50 V NOMINAL
Off-hook current	25 mA min
Terminating impedance	Configurable, including 600 ohms