Two IP phones configured in the same office have a phone call in progress when the Call Manager they are registered to fails. Which result is true?

In Cisco IP telephony, RTP audio flows directly between endpoints rather than through CUCM, so the voice path survives a call manager failure. When CUCM becomes unavailable, the phones maintain the active RTP stream by operating in a peer proxy mode, keeping the call alive without requiring CUCM involvement in the media path.

The call is not immediately disconnected because RTP is a direct peer-to-peer stream between the phones and does not depend on the CUCM signaling path remaining active.

While features like MOH and Transfer do become unavailable after CUCM failure, this answer is incomplete because it omits the specific mechanism - phones entering a proxy mode for RTP - that allows the call to remain active.

RTP/RTCP keepalives operate between the two endpoint phones, not between the phones and CUCM, so a CUCM outage does not cause the RTP keepalive to expire and disconnect the active call.