Which of the following ports can UCM use to communicate with an IP phone if the phone supports only SIP for call signaling? (Select the best answer.)

TCP port 2000 is used by the SCCP (Skinny Client Control Protocol), not SIP, so a SIP-only phone would not use this port.

UDP port 2427 is associated with MGCP (Media Gateway Control Protocol), which is unrelated to SIP endpoint registration.

SIP (Session Initiation Protocol) standardly uses port 5060 and supports both TCP and UDP as transport protocols. Cisco UCM is capable of registering and communicating with SIP endpoints using TCP port 5060 for reliable transport or UDP port 5060 for lower-overhead transport, depending on the phone and UCM configuration. Because the phone supports SIP, UCM can successfully communicate using this well-known SIP signaling port.

TCP port 6970 is used for HTTP-based phone firmware and configuration file downloads from UCM, not for SIP call signaling.

UCM can communicate with SIP-only phones using TCP or UDP port 5060, so communication is not impossible.