Appendix B SIP Call Flows
Call Flow Scenarios for Successful Calls
Step | Action | Description |
1
| to Cisco SIP IP phone B | SIP IP phone B. The INVITE request is an invitation to |
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| User B to participate in a call session. |
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| In the INVITE request: |
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| • The phone number of User B is inserted in the |
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| |
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| URL identifies the address of User B and takes a form |
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| similar to an email address (user@host where user is |
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| the telephone number and host is either a domain name |
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| or a numeric network address). For example, the |
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| |
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| appears as “INVITE |
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| user=phone.” The “user=phone” parameter |
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| distinquishes that the |
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| telephone number rather than a user name. |
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| • Cisco SIP IP phone A is identified as the call session |
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| initiator in the From field. |
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| • A unique numeric identifier is assigned to the call and |
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| is inserted in the |
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| • The transaction number within a single call leg is |
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| identified in the CSeq field. |
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| • The media capability User A is ready to receive is |
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| specified. |
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2 | 180 | Cisco SIP IP phone B sends a SIP 180 Ringing response to |
| phone B to Cisco SIP IP phone A | Cisco SIP IP phone A. |
| Cisco SIP IP Phone 7960 Administrator Guide |
|
