The Cisco VG450 High-Density Analog Gateway is a Cisco IOS-XE Software-based analog phone gateway. It connects analog phones, fax machines, modems, and speakerphones to an enterprise voice system based on Cisco Unified Communications Manager (UCM). The tight integration with the IP-based phone system is advantageous for increased manageability, scalability, and cost-effectiveness.
The FXS service modules contain an onboard DSP and don't require the router to have a dedicated Packet Voice DSP Module (PVDM) on the motherboard. The DSP on the voice module is necessary for the voice features. It also provides for echo cancellation of up to 128-ms echo-tail length for demanding network conditions.