An annunciator is automatically created in the system when the Cisco IPVMS is activated on a server. If Cisco IPVMS is deactivated, the annunciator is also deleted. A single annunciator instance can service the entire CUCM cluster if it meets the performance requirements. Additional annunciators can be configured for the cluster if necessary.
The annunciator registers with a single CUCM at a time, as defined by its device pool. It automatically fails over to a secondary CUCM if a secondary is configured for the device pool. Any announcement that is playing at the time of an outage is not maintained.
The annunciator service is responsible for the following features:
■ Cisco Multilevel Precedence Preemption (MLPP): This feature has streaming messages that it plays in response to the following call-failure conditions:
—Unable to preempt due to an existing higher-precedence call.
—A precedence (prioritization) access limitation was reached.
—The attempted precedence level was unauthorized.
—The called number is not equipped for preemption or call waiting.
■ Integration via SIP trunk: SIP endpoints can generate and send tones in-band in the RTP stream, but SCCP cannot. An annunciator is used in conjunction with an MTP to generate or accept Dual-Tone Multifrequency (DTMF) tones when integrating with a SIP endpoint.
■ Cisco IOS gateways and intercluster trunks: These devices require support for call-progress tone (ringback tone).
■ System messages: During the following call-failure conditions, the system plays a streaming message to the end user:
—A dialed number that the system cannot recognize
—A call that is not routed because of a service disruption
—A number that is busy and not configured for preemption or call waiting
■ Conferencing: During a conference call, the system plays a barge-in tone to announce that a participant has joined or left the bridge.
The annunciator is configured to support 48 simultaneous streams by default. The maximum recommended is 48 for an annunciator running on the same server with the CUCM service (call processing).
If the server has only 10-Mbps connectivity, lower the setting to 24 simultaneous streams. A standalone server without the CUCM service can support up to 255 simultaneous announcement streams, and a high-performance server with dual CPUs and a high-performance disk system can support up to 400 streams. Multiple standalone servers can be added to support the required number of streams. The maximum streams are configured in the Cisco IPVMS service parameters.
The annunciator can be configured by navigating to Media Resources > Annunciator from CUCM Administration. Figure 15-18 shows the annunciator configuration.
Figure 15-18 Annunciator Configuration
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