H.323 phones support multiple lines and can be audio, video, or data networking endpoints. H.323 terminals are synonymous with endpoints. The H.323 terminal language is used in the H.323 standard. CUCM supports voice calls from H.323 terminals natively. CUCM can also integrate with H.323 video endpoints using an H.323 gatekeeper. Cisco Unified Communications IP Telephony, Part 2 explains the H.323 video integration in further detail.
H.323 phones do not register with CUCM. H.323 devices are configured by IP address or fully qualified domain name (FQDN). H.323 gateways always show up as unregistered in CUCM. An unregistered Media Gateway Control Protocol (MGCP) is a bad thing, but H.323 gateways will always show up as unregistered because of their point-to-point nature. CUCM directs calls to the IP address of the H.323 gateway and accepts calls to the H.323 gateway over the H.225 call-control signaling TCP port 1720. There is no further integration with either H.323 gateways or gatekeepers. Third-party H.323 devices (terminals, gateways, and gatekeepers) can register with the gatekeeper or integrate directly with CUCM.
Configuration of H.323 devices must be performed on both CUCM and on the phone itself. Dial plan configuration must be configured on each device. Third-party H.323 phones consume two device license units (DLU) in CUCM.
The Cisco Unified IP Phone 7905 can be loaded with an H.323 firmware. If H.323 firmware is loaded, the phone is treated like a third-party H.323 endpoint and needs to be configured as a third-party H.323 phone, rather than as a Cisco Unified IP Phone 7905. The 7905 is an EoS device.
Examples of H.323 endpoints include Microsoft NetMeeting and H.323 video devices from Sony, Polycom, and Tanberg. H.323 endpoints often register with H.323 gatekeepers. H.323 gatekeepers contain dial plan elements and allow the devices to perform dynamic e.164 aliasing. Dynamic e.164 aliasing is a process in which the user specifies the phone number that the device is in charge of. The gatekeeper dynamically loads a configuration based on the device phone number specified.
H.323 endpoints support a small subset of features compared to Cisco IP Phones using SCCP or SIP. The features that are not supported include, but are not limited to, the following:
■ H.323 phones need to be configured by their IP address in CUCM rather than by a MAC address-based device ID.
■ Phone button templates and soft key templates are not supported. Each device user interface varies by vendor and product.
■ Telephony features and applications such as the following: —IP phone services —CUCM Assistant —Cisco Unified Video Advantage —Call Pickup —Barge —Presence
The high-level configuration steps for H.323 phone implementation are as follows:
1. The H.323 phone is added to CUCM with its IP address and directory numbers specified.
2. The H.323 phone is configured with the IP address of CUCM.
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