210-060 · Question #162
Which protocol is used between two Cisco IP phones once Cisco Unified Communications Manager Express connects a call?
The correct answer is B. RTP. Once Cisco Unified Communications Manager Express establishes a call between two IP phones, the actual voice media is transported using RTP, not the signaling protocol.
Question
Which protocol is used between two Cisco IP phones once Cisco Unified Communications Manager Express connects a call?
Options
- AH.323
- BRTP
- CSCCP
- DSIP
How the community answered
(32 responses)- A3% (1)
- B94% (30)
- C3% (1)
Why each option
Once Cisco Unified Communications Manager Express establishes a call between two IP phones, the actual voice media is transported using RTP, not the signaling protocol.
H.323 is a call signaling and control protocol used to set up calls, not to carry voice media between phones once connected.
RTP (Real-time Transport Protocol) is the standard media transport protocol used to carry encoded voice payload between endpoints after the call signaling has completed setup. Signaling protocols like SCCP or SIP only establish and tear down the call, while RTP handles the ongoing audio stream.
SCCP (Skinny Client Control Protocol) is a Cisco proprietary signaling protocol used between IP phones and Cisco UCM/CUCME for call control, not media delivery.
SIP (Session Initiation Protocol) is a signaling protocol that establishes, modifies, and terminates sessions but does not carry voice payload.
Concept tested: RTP as voice media transport protocol
Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/cube/configuration/cube-book/voi-rtp-overview.html
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