DLS phones require a router capable of supporting classes of service and GRE tunnels in order to operate at maximum voice quality and at highest degree of protection. Your router must be capable of distributing IP addresses to network devices via DHCP. The quality of your router should depend on the number of connected peripherals (workstations, DLS phones, etc.). DLS is a registered Cisco partner. We recommend using Cisco 2800 or 2900 series routers for installations with any Class A or Class B Hosted PBX Engine. Cisco 3900 or 7200 series are recommended for large call centers, high density calling and secure environments utilizing VoIP encryption.