Huawei U-SYS MRS6100 Technical Manual page 59

Technical Manual
U-SYS MRS6100 Media Resource Server
II. Transaction
SIP is a client/server protocol. A SIP transaction occurs between a client and a server
and comprises all messages from the first request to the final response sent from the
server to the client.
A normal call consists of three transactions. Call initiation consists of two operation
requests, INVITE and ACK. The former requires a response. The latter is used for
acknowledging the reception of the final response, and need not to send back a
response. Call termination consists of one operation request, BYE.
III. SIP URL
SIP uniform resource locators (URLs) are used for addressing purposes. The SIP
URL syntax is defined according to the uniform resource ID (URI) guidelines specified
in RFC 2396. The user name field could be a telephone number to support addressing
of IP telephony gateway and achieve the interworking between IP calls and PSTN.
A SIP URL has the syntax:
SIP: User name: Password @ Host: Port: Transmission Parameters: User
parameters: Method parameters: TTL parameters: Server address parameters?
header name= header value.
SIP indicates that SIP is used for the communication to the specified end system.
User name is composed of any characters. Generally, it can be a phone number or a
user name as in E-mail address.
Host is either a domain name or an IPv4 address.
Port refers to the port number to which a request message is sent. The default port
number is 5060, the public SIP port number.
Password can be included in a SIP URL, which is not recommended for the sake of
security.
Transport parameter indicates the used transport protocol, TCP or UDP. The default
transport parameter is UDP.
A function of SIP URL is to allow the host to be an IP telephony gateway with a
telephone number as the username. Because BNF syntax cannot distinguish
telephone number from general username, User parameter is added to follow the
domain name. Two values are available for this field: IP and phone. When the field is
set to phone, the username is a telephone number and the corresponding end
system is an IP telephony gateway.
Method parameter refers to the method (operation) to be used.
Lifetime parameter indicates the life of UDP multicast data packets. This parameter
is valid only when the transport parameter is set to UDP and the server address
parameter is set to multicast address.
Huawei Technologies Proprietary
5-34
Chapter 5 MGCP and SIP