Cisco is the worldwide leader in networking for the Internet. Cisco provides the broadest line of solutions for transporting data, voice and video within buildings, across campuses, or around the world. Cisco solutions ensure that networks both public and private operate with maximum performance, security, and flexibility.PVDM-256K-4U20 is a Cisco 1760-V 4 Channel to 20 Channel PVDM Factory Upgrade.