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Unattended Graceful Shutdown of Cisco Unity Express with an APC UPS

Published date: 24 July 2018

Cisco Unity Express is an essential component of the Cisco IP Communications portfolio of products. Cisco Unity Express application software, which provides voice mail and automated attendant services, is Linux based. Typically, conventional UNIX or Linux systems must be shut down orderly and gracefully before power is lost or cut. Power can be lost if the router is turned off before the application is closed or when a power failure occurs. The ungraceful shutdown of Cisco Unity Express caused by abrupt loss of AC power may, in certain cases, lead to the file system damage. For this reason, a reliable UPS is recommended to help ensure continuous power to the Cisco Unity Express module and continued IP telephony operation.

Product Line:
An APC Smart-UPS (SUA, SUM and SURTA part numbers only) in combination with the APC AP9840 shutdown serial cable

Cisco IOS Software Release 12.3(4)T or later and the IP voice image or higher are required in order to work with the APC Smart-UPS. To enable Cisco IOS Software to monitor the signal form the APC UPS, the following Cisco IOS Software configuration needs to be added to the router:

• line aux 0
• privilege level 15
• modem Dialin
• autocommand service-module service-engine <slot>/0 shutdown
• where is the Cisco Unity Express slot number


This integration is compatible with APC’s Smart-UPS™ with prefix SUA, SUM & SURTA only, using the AP9840 serial cable. The cable requires connectivity to the AUX port of the Cisco Unity Express module. The Smart-UPS will only initiate the shutdown command after its battery capacity has reached less than 5 percent.

After the loss of AC power, the APC UPS requires the shutdown signal to be asserted for at least 4 seconds before the APC UPS shuts down. Thus, a narrow window exists after Cisco Unity Express has been signaled to shut down during which the AC power may be immediately restored. If this happens, the APC UPS will not shut down the router at all. In this case, the Cisco Unity Express application is shut down, but the router is not and requires that the user manually bring the Cisco Unity Express back online.

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