Avia Tablet Accessory Avaya Custom Edition Manual de usuario descargar pdf (Pagina 29)

An INVITE request is generated and sent to John.

The INVITE message contains Session Description

Protocol (SDP) parameters that define the types of

media the caller can accept and where it wishes the

media to be sent.

2. A DNS SRV record lookup for SIP services resolves to

John’s proxy server, proxy.bigcompany.com. The

INVITE request is sent to the proxy server.

3. The server receives and processes the invitation, and

looks up Michael’s contact in the Registrar.

4. The Registrar returns host@officephone.

bigcompany.com where John is currently located.

5. The proxy server generates and sends an INVITE

request to the server [email protected]

company.com.

asks John whether he wants to accept the call.

John may hear a ring, see a text message, or see a

blinking LED.

7. John’s acceptance is sent to the proxy server.

8. The proxy server sends the acceptance to Michael.

9. Michael’s UA responds to the acceptance with an ACK

(acknowledgement), which tells the proxy server and

John’s UA that Michael is ready to start the call.

10. At the end of the conversation, John hangs up his

phone. His UAC sends a BYE message to Michael.

11. Michael’s UAC responds with a BYE message which

ends the session.

Though this call flow describes the initiation of a phone

call, the beauty of SIP is that the same basic call flow would

also apply for establishing video conferencing or other media

sessions.

SIP Communications For Dummies, Avaya Custom Edition

06_041498 ch02.qxp 3/16/06 5:52 PM Page 22

SIP guide

1 2 ... 24 25 26 27 28 29 30 31 32 33 34 ... 73 74

Sin comentarios

Avia Tablet Accessory Avaya Custom Edition Manual de usuario Pagina 29