IP Office SIP endpoint implementation is built on two major SIP components: SIP server components SIP endpoint user agent applications.
SIP servers provide SIP endpoint support to allow full interoperability between SIP endpoints, other IP telephones based on H.323, digital and analog telephones as well as IP Office trunks (analog, digital or SIP-based).
SIP servers provide centralized information and enablement services in a SIP ecosystem. The core SIP servers and their functions are summarized here.
IP Office provides the features of the following two servers for voice and fax communication.
Registrar server
When SIP IP telephones come online, they need to make sure that others are aware that they're available to take and make calls. The Registrar authenticates and registers the IP phone (often directly related to a specific user) when it comes online, and then stores information on the telephones logical identities.
Proxy server
A proxy server takes SIP requests, processes them, and passes them downstream while sending responses upstream to other SIP servers or devices. A proxy server may act as both a server and a client, and can modify a SIP request before passing it along. A proxy is involved only in the setup and teardown of a communication session. After user agents establish a session, communications occur directly between the parties.
Functionality of the following two SIP servers are generally available by
IP Office using existing
IP Office functionality. Therefore, while functionality is provided, for example, allowing hot desking in a small community network, a consistent methodology between SIP and non-SIP endpoints is used to deliver those features
Location service
As users roam, the network needs to be continually aware of their locations. The location service is a database that keeps track of users and their locations. The location service gets its input from the registrar server and provides key information to the proxy and redirect servers. IP Office provides hot desking support, delivering a similar functionality but working consistently between SIP and non SIP endpoints.
Redirect server
If users are not in their home domains, sessions bound for them needs to be redirected to them.
The redirect server maps a SIP request destined for a user to the device closest to the user. In IP Office, call forwarding and Follow me functionality is used to provide again consistent functionality between all type of endpoints.
