Device Mobility’s primary function is to dynamically apply a device’s configuration (like its Device Pool, Location, and Calling Search Space) based on the IP subnet from which it registers. This allows a user to take their phone to a different location (like the acquired company’s office) and have it automatically reconfigure for that site’s dial plan and settings, which is crucial for integrating users while preserving their DNs.

By default, CUBE operates in media flow-through mode. This means it allows the media (RTP streams) to pass directly between the endpoints without being transcoded by the CUBE itself, unless required for features like DTMF interworking or codec filtering. The `media` command is used to change this behavior to flow-around or to enable specific media services.

This scenario requires number manipulation based on the calling location. Translation Patterns are used to manipulate the dialed digits before routing. A Translation Pattern in the US office’s calling search space could prepend the international access code and UK country code. Route Patterns are then used to match the final digit string and select the appropriate gateway or trunk. Partitions and CSS control access, but don’t manipulate digits. Route Groups/Lists are for distribution, and Locations/Device Pools are for bandwidth control and device settings, not digit manipulation.

Interactive video (like video conferencing) should be marked with DSCP AF41 (Value 34). AF41 provides high-priority, low-latency forwarding suitable for real-time video. EF (Value 46) is typically reserved for voice media because it requires the absolute lowest latency and jitter. While video is sensitive, it can tolerate slightly more variation than voice. AF31 is generally used for call-signaling traffic. CS3 is a legacy IP precedence value sometimes used for signaling but not best practice for media.

On CUCME, ephone-dn is a more feature-rich, abstract configuration object representing a directory number. It can have multiple lines, call waiting, shared lines, and other advanced features, typically associated with SCCP phones. The `directory-number` command under a `voice register pool` (used for SIP phone registration) is a simpler, direct assignment of a number to a SIP endpoint, more akin to a basic line association without the complex object model of ephone-dn.

The foundational principle of CER location tracking is the switch/port-to-ERL mapping. When a phone registers (via CDP, LLDP, or switch port tracing), CER identifies the switch IP and port number. It then looks up the pre-configured mapping to determine the exact ERL for that physical port. This granular mapping is what allows CER to provide a specific location (e.g., ‘Building A, Floor 3, Cube 45B’) to the Public Safety Answering Point (PSAP).

A SIP 488 ‘Not Acceptable Here’ response is sent when the recipient of a session invitation understands the request but cannot support one or more critical aspects of the session description, most commonly the media codecs. This indicates that the codec list offered in the SDP (Session Description Protocol) of the INVITE from CUCM does not overlap with the codecs the ITSP is willing to accept. The solution is to align the codec negotiation settings on the CUCM SIP trunk and the ITSP’s configuration.

In a centralized deployment, phones at remote sites register to the central CUCM over the WAN. ‘Call Forward Unregistered’ (CFUR) is a critical resiliency feature. If the WAN link fails, the phones lose their connection to CUCM and re-register locally with the SRST gateway. CUCM, seeing the phones as unregistered, will then forward incoming calls for those lines to the number configured in CFUR (often the SRST gateway’s pilot number or a cell phone), ensuring call survivability.

Extension Mobility is enabled or disabled on a per-device basis. On the Phone Configuration page in CUCM Administration, there is a check box labeled ‘Enable Extension Mobility’. To prevent a specific phone (like a lobby or conference room phone) from being used for EM login, you simply uncheck this box for that device. This is the most direct and common method of controlling EM access per device.

Device Mobility’s primary function is to dynamically apply a device’s configuration (like its Device Pool, Location, and Calling Search Space) based on the IP subnet from which it registers. This allows a user to take their phone to a different location (like the acquired company’s office) and have it automatically reconfigure for that site’s dial plan and settings, which is crucial for integrating users while preserving their DNs.0