210-065 · Question #300
When a Multiway call excalation happens, which SIP message is sent?
The correct answer is A. REFER. A Multiway call escalation uses the SIP REFER method to instruct a participant's endpoint to join an external conferencing bridge.
Question
When a Multiway call excalation happens, which SIP message is sent?
Options
- AREFER
- BTRANSFER
- C200 OK
- DREDIRECT
How the community answered
(31 responses)- A81% (25)
- B13% (4)
- C3% (1)
- D3% (1)
Why each option
A Multiway call escalation uses the SIP REFER method to instruct a participant's endpoint to join an external conferencing bridge.
In a Multiway escalation, the initiating endpoint sends a SIP REFER message to the far-end endpoint, directing it to join a pre-configured conferencing resource (such as a TelePresence MCU or Conductor). REFER is the standard SIP transfer mechanism defined in RFC 3515 and is the correct method for redirecting a dialog to a new destination, which is exactly what Multiway requires to bridge all participants together.
TRANSFER is not a valid SIP method; call transfer in SIP is accomplished using the REFER method combined with a Refer-To header.
200 OK is a success response code, not a request method, and cannot initiate a call escalation.
REDIRECT is not a SIP request method; call redirection in SIP is handled by 3xx response codes, not a message named REDIRECT.
Concept tested: SIP REFER method in Multiway call escalation
Source: https://www.cisco.com/c/en/us/support/docs/unified-communications/telepresence-multiway/116025-configure-multiway-00.html
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