Huawei U-SYS MRS6100 Technical Manual page 60

Technical Manual
U-SYS MRS6100 Media Resource Server
Server address parameter indicates the address of the server communicating with
the user, which overwrites the address in the host field. It is usually a multicast
address.
Transport parameter, Lifetime parameter, Server address parameter, and
Method parameter are URL parameters used only in a redirect address, that is, the
Contact field which will be mentioned later.
The following are some SIP URL examples.
Sip: 55500200@182.20.1.112;
55500200 is a username. 182.20.1.112 is the IP address of an IP telephony gateway.
Sip: 55500200@127.0.0.1:5061; User=phone;
55500200 is a username. 127.0.0.1 is the IP address of a host. 5061 is a port number
of the host. The user parameter is phone, indicating the username is a telephone
number.
Sip: alice@registrar.com; method=REGISTER;
Alice is a username. registrar.com is the domain name of a host. Register is the
method parameter.
IV. User location
User location is based on registration. After a SIP user terminal is powered on, it starts
to register to a registrar. For that specific purpose, REGISTER request and
registration procedure are defined in SIP.
V. Location service
A location service is used by a SIP redirect or proxy server to obtain information about
a callee's possible location. Location services are offered by location servers.
Location servers may be co-located with a SIP server, but the manner in which a SIP
server requests location services is beyond the scope of this document.
VI. Proxy server
Proxy server is a logical network entity that acts as both a server and a client for the
purpose of forwarding requests or responses on behalf of other clients. Proxy server
may be in one of the three states: Stateless, Stateful and Call Stateful. It attempts to
forward requests to multiple addresses with a branch or cycle method.
Proxy server implements the functions of routing, authentication, charging monitoring,
call control and service provision.
VII. Redirect server
Redirect server is a server that accepts a SIP request, maps the address into zero or
several new addresses, and returns these addresses to the client. Then the client can
directly initiate requests to these new addresses again. Redirect server implements
Huawei Technologies Proprietary
5-35
Chapter 5 MGCP and SIP