Gateways provide a number of methods for connecting an IP telephony network to the public switched telephone network (PSTN), legacy PBX systems, key systems, or analogue devices. Gateways range from specialized, entry-level and standalone voice gateways to high-end, feature-rich integrated routers and Cisco Catalyst gateways. For general guidance on gateway selection and features, refer to the Cisco Collaboration System Solution Reference Network Design (SRND), available at Link.

• IPv4-only stack supported gateways with SIP protocol as shown in: Supported IPv6 Addressing Modes.

• Software and hardware media termination points (MTPs) for conversion between IPv4 and IPv6 use SCCP IPv4 signaling to Unified CM.

• All other gateway connections that use SCCP, H.323, and MGCP signaling protocols between Unified CM and the gateway have been deprecated.

• You can combine ISDN gateways, Unified SRST analog port, and MTP functionality on a single Cisco Integrated Services Router (ISR) platform. Unified SRST and CUBE cannot co-exist in the same router.

• Cisco 2800 and 3800 Series Integrated Services Routers and Cisco VG Series Gateways must be configured as IPv4-only stack gateway.