Annunciator Resources

An annunciator uses the Cisco IP Voice Media Streaming Application service and enables Cisco CallManager to play prerecorded announcements (.wav files) and tones to Cisco IP Phones, gateways, and other configurable devices. The annunciator enables Cisco CallManager to alert callers as to why a call has failed. The annunciator can also play tones for some transferred calls and some conferences.

In conjunction with Cisco CallManager, the annunciator device provides multiple one-way, RTP stream connections to devices such as Cisco IP Phones and gateways. For example, a user at extension 1001 dials extension 2503, an invalid number. The system cannot complete the call. The annunciator device plays a one-way RTP stream to extension 1001: "Your call cannot be completed as dialed. Please consult your directory and call again or ask your operator for assistance. This is a recording."

The annunciator plays the announcement or tone to support the following conditions:

• Announcement For devices that are configured for Cisco CallManager Multilevel Precedence Preemption (MLPP).
• Barge tone Before a participant joins an ad hoc conference.
• Ringback tone When you transfer a call over the PSTN through a Cisco IOS gateway, over an H.323 Intercluster Trunk, or to the SIP client from an SCCP phone, the annunciator plays the tone because the gateway cannot play the tone when the call is active.

To add an annunciator to the Cisco CallManager, you must activate the Cisco IP Voice Media Streaming Application service on the server where you want the annunciator to exist in the cluster.

Table 15-5 shows sample annunciator announcements.

For a single annunciator, Cisco CallManager sets the default maximum to 48 simultaneous streams, as indicated in the annunciator service parameters (accessed under the service parameters for the Voice Media Streaming Application). It is recommended that you not exceed 48 annunciator streams on a coresident server where the Cisco CallManager and Cisco IP Voice Media Streaming Application services run. If the server has only 10-Mbps connectivity, lower the setting to 24 simultaneous streams.

If the annunciator runs on a standalone server where the Cisco CallManager service does not run, the annunciator can support up to 255 simultaneous announcement streams. If the standalone server has dual CPUs and a high-performance disk system (as in the case of the 7845 MCS server), the annunciator can support up to 400 simultaneous announcement streams. You can add multiple standalone servers to support the required number of streams.

Each annunciator can support G.711 a-law, G.711 mu-law, wideband, and G.729 codec formats. A separate .wav file exists for each codec that is supported.

Annunciator Configuration

Because the annunciator service requires access to a large amount of audio files, only the Cisco CallManager can act as an annunciator in the cluster. There are no hardware-based resources that exist. When you activate the Cisco IP Voice Media Streaming Application service in Cisco CallManager Serviceability, Cisco CallManager automatically adds the annunciator device to the server configuration.

The annunciator configuration is almost identical to the MTP configuration. Minimally, you must select a host server, enter the annunciator name, and assign the annunciator to a device pool, as shown in Figure 15-3.

Figure 15-3. Annunciator Configuration Window

Each annunciator registers with only one Cisco CallManager at a time. The system might have multiple annunciators, depending on your configuration, each of which can register with different Cisco CallManager servers, depending on the device pool to which you have assigned the annunciator service. Each annunciator belongs to a device pool. The device pool associates the secondary (backup) Cisco CallManager and the region settings.

When you update or configure the annunciator service parameters, the changes automatically occur when the annunciator becomes idle, when no active announcements are played.