原创 1224 Structure of the Protocol
SIP is structured as a layered protocol, which means that its behavior is described in terms of a set of fairly
2020-07-02 17:39:43
1
原创 1223 REGISTER01
No ACK is sent - an ACK is only sent in response to a response to an INVITE request Registration is another common ope
2020-07-02 17:39:42
原创 1222 sending a re-INVITE to change the session
The other party sends a 200 (OK) to accept the change. The requestor responds to the 200 (OK) with an ACK. If the
2020-07-02 17:39:42
原创 1228 Generating the Request
A valid SIP request formulated by a UAC MUST, at a minimum, contain the following header fields: To, From, CSeq,
2020-07-02 17:39:42
原创 1220 SIP is not a vertically integrated communications system.
SIP is rather a component that can be used with other IETF protocols to build a complete multimedia architecture.
2020-07-02 17:39:41
5
原创 1225 TU layer
saction layer is called the transaction user (TU). Each of the SIP entities, except the stateless proxy, is a t
2020-07-02 17:39:41
原创 1231 Sending the Request
Local policy MAY specify an alternate set of destinations to attempt. If the Request-URI contains a SIPS URI, any a
2020-07-02 17:39:40
原创 1226 SIP Messages
Both types of messages consist of a start-line, one or more header fields, an empty line indicating the end of the
2020-07-02 17:39:39
1
原创 1221 Additional Via
Before forwarding the request, the atlanta.com proxy server adds an additional Via header field value that cont
2020-02-21 05:38:49
原创 1219 Response Codes 01
486 忙 The callee's end system was contacted successfully, but the callee is currently not willing or able to take a
2020-02-21 05:38:49
原创 1229 Call-ID
The Call-ID header field acts as a unique identifier to group together a series of messages. It MUST be the same f
2020-02-21 05:38:48
原创 0107 UAS Applying Extensions
A UAS that wishes to apply some extension when generating the response MUST NOT do so unless support for that ex
2020-02-21 05:38:48
原创 1227 Status-Line，Header
Status-Line = SIP-Version SP Status-Code SP Reason-Phrase CRLF 例如： SIP/2.0 200 OK header =
2020-02-21 05:38:48
原创 1230 Via
x The Via header field indicates the transport used for the transaction and identifies the location where the respon
2020-02-21 05:38:48
原创 0101 Processing Responses
Responses are first processed by the transport layer and then passed up to the transaction layer. The transaction
2020-02-21 05:38:48