Cisco 7960G Administrator's Manual page 151

Appendix B SIP Call Flows
Figure B-23 Authentication Error
SIP IP
Phone User A
Step Action
1. INVITE—Phone A to SIP proxy
server
2. 407 Authentication Error—SIP
proxy server to Phone A
ACK—Phone A to SIP proxy
3.
server
4. Resend INVITE—Cisco SIP IP
phone A to SIP proxy server
IP
1. INVITE B
2. 407 Authentication Error
3. ACK
4. Resend INVITE B
Description
Phone A sends a SIP INVITE request to the SIP proxy server. The request is an
invitation to B to participate in a call session. In the INVITE request:
The phone number of B is inserted in the Request-URI field in the form of a
•
SIP URL. The SIP URL identifies the address of User B and takes a form
similar to an e-mail address (user@host, where user is the telephone number
and host is either a domain name or a numeric network address). For example,
the Request-URI field in the INVITE request to User B appears as "INVITE
sip:555-0199@companyb.com; user=phone." The "user=phone" parameter
distinquishes that the Request-URI address is a telephone number rather than
a username.
Phone A is identified as the call session initiator in the From field.
•
A unique numeric identifier is assigned to the call and is inserted in the
•
Call-ID field.
The transaction number within a single call leg is identified in the CSeq field.
•
The media capability User A is ready to receive is specified.
•
The SIP proxy server sends a SIP 407 Authentication Error response to Phone A.
Phone A sends a SIP ACK to the SIP proxy server acknowledging the 407 error
message.
Phone A resends a SIP INVITE to the SIP proxy server with authentication
credentials.
Proxy
Server
IP Network
Cisco SIP IP Phone Administrator Guide, Release 6.x and 7.x
Call Flow Scenarios for Failed Calls
SIP IP
Phone User B
IP
B-55