Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility

Publisher

Cisco Systems

URL

https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/cucm_b_feature-configuration-guide-for-15/cucm_m_configure-device-mobility-1251.html

Published

2026-09-16

Updated

unknown

Accessed

2026-09-24

HTTP status

200

License

Cisco documentation; all rights reserved; no-redistribution; short excerpts and locators only

Source notes citing this source

• When a device roams into a different device mobility group, Unified CM uses the Calling Search Space, AAR Group and AAR CSS from the phone record rather than from the roaming location. in context
• For a roaming device, Device Mobility replaces the device's Location and Region, along with other device pool settings such as SRST Reference and Media Resource Group List, with values from the dynamically assigned device pool. in context
• For a phone roaming into a different device mobility group, a call that AAR reroutes after a CAC rejection is placed with the home AAR Group and AAR CSS, while the CAC decision itself uses the roaming site's location. inferred in context
• Cisco states that when a mobile user moves to another location, call admission control can protect audio and video quality by applying the bandwidth allocations of that location. in context
• Because Location is a roaming-sensitive setting, a roaming phone's calls are counted against the roaming site's CAC location, not its home location, whether or not it has changed device mobility group. inferred in context
• When the Call Forward All CSS activation policy uses the device and line CSS, a phone roaming within its device mobility group gets the roaming pool's Device Mobility CSS plus the line CSS as its CFA CSS; at home, or when roaming across groups, the home CSS is used. in context
• Unified CM always uses the Communications Manager Group from the phone record, so a roaming device still registers to its home Unified CM servers. in context
• Cisco lists calling party normalization as a Device Mobility interaction that improves dialing and callback across geographic locations by presenting a suitable calling number. in context
• For a roaming device, the Calling Party Transformation CSS from the roaming device pool overrides the device-level setting even if 'Use Device Pool Calling Party Transformation CSS' is unchecked on the phone. in context
• When a phone roams into a different device mobility group, it uses the Calling Search Space, AAR Group and AAR CSS from its phone record rather than the roaming device pool, but it still takes the roaming-sensitive settings such as Location, Region and MRGL from the roaming pool. in context
• Cisco defines a device mobility group as a logical group of sites with similar dialing patterns, for example one group for the United States and another for the United Kingdom. in context
• Cisco positions device mobility groups for networks that span countries, so users keep their configured dial plan wherever they roam. in context
• A phone needs a dynamic IP address to use Device Mobility; if a phone with a static IP address roams, Unified CM keeps using the settings from its home location. in context
• When a phone roams into a different device mobility group it keeps its home CSS, so an emergency call routed only by that CSS could leave through the home site's gateway unless the dial plan or an emergency solution sends it out locally. inferred in context
• Phones with only an IPv4 stack or only an IPv6 stack are associated with a device pool using Device Mobility Info entries that match their addressing mode. in context
• Device Mobility swaps only the device-level CSS, so any site-specific PSTN or emergency routing reached through a line CSS stays tied to the home site when the phone roams. inferred in context
• When a device's IP address matches more than one Device Mobility Info subnet, Unified CM picks the subnet with the most bits in its mask (longest match rule); for example 9.9.8.2 matches 9.9.8.0/24 rather than 9.9.0.0/16. in context
• Physical locations are configured under System > Physical Location, device mobility groups under System > Device Mobility > Device Mobility Group, and subnet-to-device-pool mappings under System > Device Mobility > Device Mobility Info. in context
• The phone-level Device Mobility Mode can be On, Off or Default, and Default makes the phone follow the clusterwide Device Mobility Mode service parameter. in context
• Device Mobility is turned on clusterwide with the Device Mobility Mode service parameter of the Cisco CallManager service (System > Service Parameters), or per phone with the Device Mobility Mode field on the Phone Configuration page. in context
• If a device gets its IP address through NAT or PAT, the address it presents at registration may not match its real address, so Device Mobility subnet matching can fail. in context
• If no Device Mobility Info entry matches the device's IP address, the device uses the settings of its home device pool. in context
• Cisco lists as prerequisites SCCP or SIP phones, the Cisco Database Layer Monitor running on the same node as Cisco CallManager, Cisco TFTP running on at least one node, and device pools configured with site-specific settings. in context
• Device Mobility lets a roaming device take on the site-specific settings of the site it has moved to: Unified CM matches the device's IP address against the subnets configured for Device Mobility to work out its physical location and assign a device pool. in context
• Because Region is roaming-sensitive, a roaming phone's codec and bit-rate selection follows the region of the roaming device pool. inferred in context
• The device pool's Device Mobility Related Information settings are Device Mobility Calling Search Space, AAR Calling Search Space, AAR Group and Calling Party Transformation CSS. in context
• When a phone returns to its home location, Unified CM removes the roaming device pool, downloads the home configuration and resets the device. in context
• The roaming-sensitive device pool settings, which a roaming device always takes from the roaming device pool, are Date/Time Group, Region, Location, Network Locale, SRST Reference, Connection Monitor Duration, Physical Location, Device Mobility Group and Media Resource Group List. in context
• If more than one device pool is associated with the matching subnet, Unified CM assigns the roaming device pool round-robin. in context
• When a phone roams to a site in the same device mobility group, it takes the Device Mobility CSS, AAR Group and AAR CSS from the roaming device pool, so it can reach the local gateway. in context
• If the matching subnet's device pool has the same physical location as the home device pool, the phone is not treated as roaming and keeps its home device pool settings. in context
• If the matching subnet has a single device pool that differs from the home device pool and has a different physical location, the phone is treated as roaming and re-registers with that device pool's parameters. in context
• Because SRST Reference is roaming-sensitive, a roaming phone that loses its WAN connection to Unified CM would fall back to the SRST reference of the roaming device pool, the local site's SRST, rather than its home site's. inferred in context
• The CUCM 15 task flow for Device Mobility is: enable Device Mobility, configure physical locations, configure device mobility groups, configure device pools, configure Device Mobility Info, then view the roaming device pool parameters. in context
• On the Phone Configuration page, View Current Device Mobility Settings shows the roaming device pool settings, or the home settings if the device is not roaming. in context
• Even while a device is roaming, Unified CM always uses the Communications Manager Group setting from the phone record, never from the roaming device pool. in context
• When a device roams to a different device mobility group, Unified CM uses the Calling Search Space, AAR Group and AAR CSS from the phone record, not from the roaming location. in context
• Device Mobility requires the phone to have a dynamic IP address. Phones with static IP addresses keep their home location settings when they roam. in context
• If the device pool of the matching subnet is the device's home device pool, the device stays in its home location; otherwise it is treated as roaming and gets the matching subnet's device pool settings. in context
• Device Mobility uses the longest-match rule for subnets: an address such as 9.9.8.2 matches 9.9.8.0/24 rather than 9.9.0.0/16. in context
• The clusterwide Device Mobility Mode service parameter sets the default. Each phone can be set to On, Off or Default, where Default follows the service parameter. in context
• NAT or PAT between the phone and Unified CM can prevent Device Mobility from matching the phone's IP address to the correct subnet. in context
• The Device Mobility Related settings are the AAR Group, the AAR Calling Search Space and the Device Mobility Calling Search Space. They are taken from the roaming device pool only when the device roams within the same device mobility group. in context
• When a device roams, the Device Mobility roaming-sensitive settings come from the roaming device pool: Date/Time Group, Region, Location, Network Locale, SRST Reference, Connection Monitor Duration, Physical Location, Device Mobility Group and Media Resource Group List. in context
• With Device Mobility, Unified CM matches a device's IP address against configured IP subnets to find its physical location and assign the device pool tied to that subnet. in context
• Cisco's Device Mobility task flow runs in this order: enable Device Mobility, configure physical locations, configure device mobility groups, configure device pools for Device Mobility, then configure Device Mobility Information (subnet-to-device-pool mappings). in context

Cite this source record

APA

WarmTransfer. (2026, September 16). Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility. WarmTransfer. https://warmtransfer.net/knowledge/sources/cisco-cucm-featconfig-15-device-mobility

BibTeX

@misc{warmtransfer-cisco-cucm-featconfig-15-device-mobility,
  title  = {Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/sources/cisco-cucm-featconfig-15-device-mobility},
  note   = {Cisco Systems, accessed 2026-09-24}
}