In the event of an AC power outage, this rechargeable lithium-ion battery automatically and instantaneously continues to power the Voice over Internet Protocol (VoIP) functionality of the Pace router, enabling emergency calls to be made during the outage (the battery does not fully power the router during an outage). The battery provides up to 8 hours of VoIP standby time in the event of an outage. The battery assembly is installed in the battery compartment of the router.