Which method does a Cisco Unified 9971 phone use to send keep-alive messages to Cisco Unified Communications Manager?
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A. B. C. D. E.C.
Phone registers with primary and establishes keepalive connection with secondary.
Expires = 0 keepalive mechanism allows Cisco SIP Phones to more closely resemble the failover / fallback behavior of SCCP.
The Cisco Unified 9971 phone uses SIP (Session Initiation Protocol) to communicate with the Cisco Unified Communications Manager (CUCM) and to send keep-alive messages to maintain the registration status of the phone.
Out of the given options, the correct method that the Cisco Unified 9971 phone uses to send keep-alive messages to CUCM is option B, SIP OPTIONS.
SIP OPTIONS is a message used for checking the status of the remote end and its capabilities. This message contains a small message body and is sent periodically to check if the remote endpoint is still available and ready to receive calls. When the phone sends a SIP OPTIONS message to CUCM, CUCM responds with a SIP 200 OK message, indicating that the phone is still registered and available.
Option A, SIP NOTIFY with Event set to keep-alive, is used for sending unsolicited notifications from a SIP endpoint to a SIP server. It is not used for sending keep-alive messages.
Option C, SIP REGISTER with Expires set to zero, is used to unregister a SIP endpoint from a SIP server. It is not used for sending keep-alive messages.
Option D, SCCP StationRegister, is a message used by SCCP (Skinny Client Control Protocol) phones to register with the CUCM. It is not used for sending keep-alive messages by SIP phones.
Option E, SCCP StationServerReq, is a message used by SCCP phones to request a list of available servers from CUCM. It is not used for sending keep-alive messages by SIP phones.