Yealink SIP-T4X, Руководство администратора

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Appendix
409
Step Action Description
specified.
F2
INVITE—Proxy Server to User
B
The proxy server maps the SIP URI in the
To field to User B. Proxy server forwards
the INVITE message to User B.
F3
100 Trying—User B to Proxy
Server
User B sends a SIP 100 Trying response
to the proxy server. The 100 Trying
response indicates that the INVITE
request has been received by User B.
F4
100 Trying—Proxy Server to
User A
The proxy server forwards the SIP 100
Trying to User A to indicate that the
INVITE request has already been
received.
F5
486 Busy Here—User B to
Proxy Server
User B sends a SIP 486 Busy Here
response to the proxy server. The 486
Busy Here response is a client error
response indicating that User B is
successfully connected but User B is
busy on the IP phone and unable or
unwilling to take the call.
F6
486 Busy Here—Proxy Server
to User A
The proxy server forwards the 486 Busy
Here response to notify User A that User
B is busy.
F7 ACK—User A to Proxy Server
User A sends a SIP ACK to the proxy
server. The SIP ACK message indicates
that User A has received the 486 Busy
Here message.
F8 ACK—Proxy Server to User B
The proxy server forwards the SIP ACK
to User B to indicate that the 486 Busy
Here message has already been
received.