Polycom Version 2.0.3B manual Terminology, SIP 2.0 Administrators Guide

Technical Bulletin

SoundPoint ® IP, SIP 2.1

Terminology

	Before you read this document, it is important to understand certain
	terminology and become familiar with the server/registration configuration
	as described in the references listed in the References on page 8. The behavior
	described in this document supersedes that described in section 3.6.5 of the
	SIP 2.0 Administrator's Guide.
	SIP Registrations: SoundPoint IP phones support the ability to have multiple
	SIP Registrations per phone. This is often used to support multiple “Lines” on
	a single phone and normally the SIP server(s) used for each Registration are
	the same. However, they could be different.
	Primary and Fallback Servers: Each of these SIP Registrations may be
	configured for concurrent registration with multiple servers for fallback
	purposes. For example, a phone may be configured to have two SIP
	Registrations and each SIP Registration may be configured with two separate
	servers (a primary server and a fallback server). DNS mechanisms (as
	described in RFC3263) may be used such that the servers are capable of
	resolving to multiple physical SIP servers for fail-over purposes.
Note
	The primary server is the only one that will be used for advanced SIP features such
	as shared lines, message waiting indicators, and presence. This is a change in
	behavior from software releases before SIP 2.1 All other configured servers are
	referred to as fallback servers.
	Working Server: The phone maintains a list of all possible servers gained from
	both DNS and configuration. The highest priority server which has an active
	registration is treated as the working server and will be the first server tried for
	call initiation purposes. At any time, there is only one working server
	recognized by the phone.
	Registrar Server: Servers (both primary and fallback) may be configured with
	registration enabled or disabled using the reg.x.server.y.register
	configuration parameter. Servers that have this parameter enabled will
	attempt registrations and are termed a registrar server. If a server is not a
	registrar server, calls will be attempted on that server if appropriate, but
	registration will not be attempted. Only a registrar server can become the
	working server.
	For the purposes of this document, we will use examples where the phone has
	only one SIP Registration.
	The sections Server <server/> on page 95 and Registration <reg/> on page 149
	of the SIP 2.0 Administrator's Guide describe the parameters that are relevant to
	the configuration of the phones for server redundancy and fallback behavior.
	Configuration file changes for SIP 2.1 are described in Configuration File
	Changes on page 7.

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