What is required to configure NTP on a Cisco Unified Communications Manager publisher to support SIP phones?

Question

Options

• AConfigure Phone NTP References in Cisco Unified CM Administration.
• BConfigure the NTP server in Cisco Unified OS Administration
• CConfigure the NTP server in Cisco Unified CM Administration.
• DConfigure time in Cisco Unified OS Administration.
• ERestart the Unified Communications Manager services for the publisher and subscribers on the

• A
  94% (33)
• C
  3% (1)
• D
  3% (1)

Explanation

SIP phones rely on the CUCM publisher for time synchronization differently than SCCP phones. For SIP phones, you must configure 'Phone NTP References' in Cisco Unified CM Administration (the web-based call manager admin interface). This tells SIP phones which NTP server to use directly. This is distinct from SCCP phones, which get their time from the OS-level clock of CUCM itself (requiring NTP to be set in Cisco Unified OS Administration). Simply configuring OS-level NTP or setting the time in OS Administration is insufficient for SIP phone time sync - the Phone NTP Reference must be explicitly defined.

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