# Unified CM Device Mobility

Canonical: https://warmtransfer.net/knowledge/cucm-device-mobility

Last verified: 2026-09-25

Device Mobility allows a roaming device to take on site-specific parameters from the location it has moved to[^36]. Unified CM evaluates the device's IP address against configured subnets to identify its physical location and assign an appropriate device pool[^36].

## How it works

When evaluating an endpoint's registration IP address, Unified CM applies a longest match rule to entries configured under Device Mobility Info, selecting the entry with the most bits in its subnet mask[^27]. For instance, IP address 9.9.8.2 matches 9.9.8.0/24 instead of 9.9.0.0/16[^27]. If no entry matches the IP address, the endpoint retains the settings of its home device pool[^32].

To use Device Mobility, a phone must receive a dynamic IP address; if a phone configured with a static IP address moves, Unified CM maintains its home location settings[^16]. When an endpoint obtains its address via NAT or PAT, the address presented at registration may differ from its actual address, causing subnet matching to fail[^31]. For endpoints operating solely on an IPv4 stack or an IPv6 stack, association with a device pool relies on Device Mobility Info entries matching their addressing mode[^25].

Endpoint assignment scenarios follow specific criteria:
- If the matching subnet's device pool shares the same physical location as the home device pool, the device is not treated as roaming and keeps its home device pool parameters[^43].
- If the matching subnet points to a single device pool that differs in identity and physical location from the home pool, the phone is classified as roaming and re-registers using that device pool's parameters[^44].
- If multiple device pools map to the matching subnet, Unified CM distributes the assignment using round-robin selection[^41].
- When a phone returns to its home location, Unified CM strips the roaming device pool, applies the home configuration, and resets the endpoint[^39].

Unified CM consistently uses the Communications Manager Group defined directly on the phone record, ensuring that a roaming device maintains registration to its home Unified CM servers[^9].

## Device pool settings and device mobility groups

The roaming-sensitive settings, which are always acquired from the roaming device pool, consist of Date/Time Group, Region, Location, Network Locale, SRST Reference, Connection Monitor Duration, Physical Location, Device Mobility Group, and Media Resource Group List[^40]. WarmTransfer's reading of the sources is that because Region and Location are roaming-sensitive, codec and bit-rate selection follow the roaming pool's region, while CAC bandwidth tracking applies against the roaming site's location[^5][^37]. WarmTransfer's reading of the sources is that if a roaming device loses its WAN link to Unified CM, it fails over to the SRST reference configured on the roaming device pool rather than the home reference[^45].

The device pool's Device Mobility Related Information parameters include Device Mobility Calling Search Space, AAR Calling Search Space, AAR Group, and Calling Party Transformation CSS[^38]. Cisco defines a device mobility group as a logical collection of sites with similar dialing patterns (such as one group for the United States and another for the United Kingdom) and positions them for multinational deployments to preserve user dial plans[^14][^15]. 

When a phone roams within the same device mobility group, it inherits the Device Mobility CSS, AAR Group, and AAR CSS from the roaming device pool to access local gateways[^42]. If the Call Forward All (CFA) CSS activation policy combines device and line CSSs, a phone roaming within its device mobility group receives the roaming pool's Device Mobility CSS plus the line CSS as its CFA CSS[^8].

When a phone roams across different device mobility groups, it retains the Calling Search Space, AAR Group, and AAR CSS from its phone record, while still inheriting roaming-sensitive parameters such as Location, Region, and MRGL from the roaming pool[^13]. When roaming across groups or located at home, CFA CSS uses the home CSS[^8]. WarmTransfer's reading of the sources is that when an alternate call is triggered via Automated Alternate Routing (AAR) following CAC rejection across different device mobility groups, the rerouted call uses the home AAR Group and AAR CSS while the CAC check uses the roaming site's location[^1].

For Calling Party Transformation CSS, the setting from the roaming device pool overrides the device-level configuration on a roaming endpoint, even if "Use Device Pool Calling Party Transformation CSS" is unchecked on the phone[^11]. Cisco lists calling party normalization as a feature interaction that improves callback and dialing across geographic locations[^10].

## Configuration and troubleshooting

Prerequisites for Device Mobility comprise SCCP or SIP endpoints, the Cisco Database Layer Monitor service running on the same node as Cisco CallManager, Cisco TFTP active on at least 1 cluster node, and device pools provisioned with site-specific settings[^35].

The standard configuration workflow in CUCM 15 involves enabling Device Mobility, defining physical locations, defining device mobility groups, configuring device pools, configuring Device Mobility Info entries, and viewing the resulting roaming parameters[^46]. Administration paths are:
- Physical locations: **System > Physical Location**[^28]
- Device mobility groups: **System > Device Mobility > Device Mobility Group**[^28]
- Subnet mappings: **System > Device Mobility > Device Mobility Info**[^28]

Device Mobility can be enabled clusterwide via the Device Mobility Mode service parameter under the Cisco CallManager service (**System > Service Parameters**), or individually on the phone record[^30]. The phone-level Device Mobility Mode supports values of On, Off, or Default, where Default adopts the clusterwide service parameter[^29]. Administrators can inspect applied values by navigating to **View Current Device Mobility Settings** on the Phone Configuration page, which displays roaming settings or home settings depending on current roaming state[^47].

In Cisco TAC troubleshooting documentation, physical locations are identified as labels that control roaming device pool selection, and roaming pool assignment failed when Physical Location was set to None[^33][^34]. TAC advises placing calling search spaces on the device rather than the directory-number line CSS and configuring a roaming CSS so roaming phones can place calls[^12]. WarmTransfer's reading of the sources is that because Device Mobility replaces only the device-level CSS, any site-specific PSTN or emergency routing placed on a line CSS remains associated with the home location[^26].

## Interactions with call control and emergency services

Cisco states that applying location bandwidth allocations via Call Admission Control (CAC) protects audio and video quality when mobile users change locations[^4]. Enhanced Locations CAC manages bandwidth across topologies and intercluster trunks by modeling links and locations; it requires the Cisco Location Bandwidth Manager feature service to run on at least 1 node (disabled by default)[^22][^23]. Automated Alternate Routing (AAR) reroutes calls over the PSTN or secondary networks if CAC blocks them due to insufficient location bandwidth, avoiding manual redialing[^3]. AAR is enabled clusterwide through the Automated Alternate Routing Enable service parameter under the CCM Automated Alternate Routing area[^2].

Unified CM Emergency Call Handler supports up to 100 ELINs per cluster and assigns outbound emergency routing based on the roaming device pool's ELIN Group[^21][^17]. An ELIN Group can be defined at the device pool level or overridden at the device level[^18]. Emergency Call Handler also routes PSAP callbacks to the endpoint that originated the emergency call if an Extension Mobility user remains logged in[^19]. Cisco instructs administrators not to enable Emergency Call Handler if an external solution like Cisco Emergency Responder (CER) is deployed[^20]. CER routes emergency traffic based on endpoint location, tracking devices through switch port, IP subnet, wireless access point, or manual line-to-ERL mappings[^7][^6].

## See also

See also [Unified CM device pools and device configuration model](https://warmtransfer.net/knowledge/cucm-device-pools).
See also [Unified CM dial plan partitions and calling search spaces](https://warmtransfer.net/knowledge/cucm-dial-plan).

## Applicability

Applies to: Cisco Unified Communications Manager and Cisco Emergency Responder. Deployments: on-premises. Sources checked 2026-09-25.

## What remains uncertain

How Cisco Emergency Responder routes emergency calls from Device Mobility roaming phones and whether the phone CSS must still reach the CER route point is not covered by the sources below.

Precedence between a device-level ELIN group and the roaming device pool ELIN group in Emergency Call Handler is not covered by the sources below.

The exact outcome when physical location is undefined in the home pool or in the roaming pools is not covered by the sources below.

Whether Webex Calling or Dedicated Instance offers an equivalent of Device Mobility and how migrations map it is not covered by the sources below.

Whether the Standard Local Route Group follows the roaming device pool and how that affects PSTN and emergency egress across device mobility groups is not covered by the sources below.

The factory default of the Device Mobility Mode service parameter is not covered by the sources below.

Device Mobility behaviour for VPN phones and Jabber and for Expressway MRA endpoints is not covered by the sources below.

Interaction between Extension Mobility login and Device Mobility roaming settings is not covered by the sources below.

## Sources

[^1]: 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). Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, device mobility groups (USA to UK example) and roaming-sensitive settings list. Checked 2026-09-25.
[^2]: AAR is turned on by setting the clusterwide Automated Alternate Routing Enable service parameter (System - CCM Automated Alternate Routing area) to True. Source: [System Configuration Guide for Cisco Unified Communications Manager Release 15 and SUs - Configure Call Routing](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/15/systemConfig/cucm_b_system-configuration-guide-15/cucm_b_system-configuration-guide-14_chapter_010010.html), Configure Call Routing, Automated Alternate Routing task flow, enable AAR step. Checked 2026-09-25.
[^3]: Automated Alternate Routing reroutes a call through the PSTN or another network when Unified CM blocks it for lack of location bandwidth, so the caller does not have to hang up and redial. Source: [System Configuration Guide for Cisco Unified Communications Manager Release 15 and SUs - Configure Call Routing](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/15/systemConfig/cucm_b_system-configuration-guide-15/cucm_b_system-configuration-guide-14_chapter_010010.html), Configure Call Routing, Automated Alternate Routing overview. Checked 2026-09-25.
[^4]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, benefits for roaming mobile devices. Checked 2026-09-25.
[^5]: 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). Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, roaming-sensitive settings list and device mobility group examples. Checked 2026-09-25.
[^6]: Cisco Emergency Responder routes emergency calls according to the location of the phone that placed the call. Source: [Cisco Emergency Responder Administration Guide, Release 15 and SUs - Plan for Cisco Emergency Responder](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cer/15/english/administration/guide/cer0_b_cisco-emergency-responder-administration-guide-15/cer0_b_cisco-emergency-responder-administration-guide-1401_chapter_01.html), Plan for Cisco Emergency Responder, overview of emergency call handling. Checked 2026-09-25.
[^7]: Cisco Emergency Responder tracks phones by switch port (MAC address behind a switch port), IP subnet, wireless access point or manual assignment of a line to an ERL. Source: [Cisco Emergency Responder Administration Guide, Release 15 and SUs - Plan for Cisco Emergency Responder](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cer/15/english/administration/guide/cer0_b_cisco-emergency-responder-administration-guide-15/cer0_b_cisco-emergency-responder-administration-guide-1401_chapter_01.html), Plan for Cisco Emergency Responder, phone tracking methods. Checked 2026-09-25.
[^8]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Interactions table, Calling Party Normalization row. Checked 2026-09-25.
[^9]: Unified CM always uses the Communications Manager Group from the phone record, so a roaming device still registers to its home Unified CM servers. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, note on Communications Manager Group. Checked 2026-09-25.
[^10]: Cisco lists calling party normalization as a Device Mobility interaction that improves dialing and callback across geographic locations by presenting a suitable calling number. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Interactions table, Calling Party Normalization row. Checked 2026-09-25.
[^11]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Configure a Device Pool for Device Mobility, note on Calling Party Transformation CSS. Checked 2026-09-25.
[^12]: The TAC technote advises that the phone use a device CSS rather than a directory-number line CSS for Device Mobility, and that a roaming CSS be configured so the roaming device can place calls. Source: [Configure and Troubleshoot Device Mobility](https://www.cisco.com/c/en/us/support/docs/unified-communications/unified-communications-manager-callmanager/211535-Configure-and-Troubleshoot-Device-Mobili.html), Configure section, notes after device pool configuration. Checked 2026-09-25.
[^13]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, device mobility groups (USA to UK example). Checked 2026-09-25.
[^14]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, device mobility groups. Checked 2026-09-25.
[^15]: Cisco positions device mobility groups for networks that span countries, so users keep their configured dial plan wherever they roam. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, device mobility groups. Checked 2026-09-25.
[^16]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview; Device Mobility Restrictions table, IP Address row. Checked 2026-09-25.
[^17]: Emergency Call Handler supports at most 100 ELINs per cluster. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Emergency Call Handler](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/cucm_b_feature-configuration-guide-for-15/cucm_mp_e9297459_00_emergency-call-handler-12-0.html), Emergency Call Handler Restrictions. Checked 2026-09-25.
[^18]: An Emergency Location (ELIN) Group can be assigned to a device pool on the Device Pool Configuration page, and a device-level assignment overrides the device pool one. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Emergency Call Handler](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/cucm_b_feature-configuration-guide-for-15/cucm_mp_e9297459_00_emergency-call-handler-12-0.html), Emergency Call Handler Configuration Task Flow, device pool and device ELIN group assignment. Checked 2026-09-25.
[^19]: Emergency Call Handler routes a PSAP callback with the caller's Extension Mobility state in mind, returning it to the device that placed the emergency call if the user is still logged in there. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Emergency Call Handler](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/cucm_b_feature-configuration-guide-for-15/cucm_mp_e9297459_00_emergency-call-handler-12-0.html), Emergency Call Handler Interactions, Extension Mobility. Checked 2026-09-25.
[^20]: Cisco says not to enable Emergency Call Handler if an external emergency calling solution such as Cisco Emergency Responder is already in use. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Emergency Call Handler](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/cucm_b_feature-configuration-guide-for-15/cucm_mp_e9297459_00_emergency-call-handler-12-0.html), Emergency Call Handler, enablement note and service parameter description. Checked 2026-09-25.
[^21]: With the Unified CM Emergency Call Handler, a roaming device uses the ELIN Group of its roaming device pool for outbound emergency calls. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Emergency Call Handler](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/cucm_b_feature-configuration-guide-for-15/cucm_mp_e9297459_00_emergency-call-handler-12-0.html), Emergency Call Handler, Device Mobility interaction and ELIN group configuration. Checked 2026-09-25.
[^22]: Enhanced Locations CAC controls audio quality and video availability across complex WAN topologies, including intercluster networks, by modelling locations and links with bandwidth limits. Source: [System Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Configure Enhanced Locations Call Admission Control](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/15/systemConfig/cucm_b_system-configuration-guide-15/cucm_b_system-configuration-guide-14_chapter_01101.html), Enhanced Locations Call Admission Control Overview. Checked 2026-09-25.
[^23]: Enhanced Locations CAC needs the Cisco Location Bandwidth Manager feature service running on at least one cluster node, and that service is off by default. Source: [System Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Configure Enhanced Locations Call Admission Control](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/15/systemConfig/cucm_b_system-configuration-guide-15/cucm_b_system-configuration-guide-14_chapter_01101.html), Enhanced Locations CAC prerequisites / task flow, Location Bandwidth Manager service. Checked 2026-09-25.
[^24]: 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). Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, device mobility groups (USA to UK example). Checked 2026-09-25.
[^25]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Restrictions table, IP Address row. Checked 2026-09-25.
[^26]: 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). Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Related Information settings (Device Mobility CSS replaces the device CSS); Device Mobility Interactions table, CFA CSS combines Device Mobility CSS with the line CSS. Checked 2026-09-25.
[^27]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, subnet matching description and 9.9.8.2 example. Checked 2026-09-25.
[^28]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Configuration Task Flow, individual task procedures. Checked 2026-09-25.
[^29]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Configuration Task Flow, Enable Device Mobility for an Individual Phone. Checked 2026-09-25.
[^30]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Configuration Task Flow, Enable Device Mobility. Checked 2026-09-25.
[^31]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Restrictions table, IP Address row. Checked 2026-09-25.
[^32]: If no Device Mobility Info entry matches the device's IP address, the device uses the settings of its home device pool. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, note on non-matching IP addresses. Checked 2026-09-25.
[^33]: The TAC technote describes physical locations as labels that nonetheless determine which roaming device pool is selected. Source: [Configure and Troubleshoot Device Mobility](https://www.cisco.com/c/en/us/support/docs/unified-communications/unified-communications-manager-callmanager/211535-Configure-and-Troubleshoot-Device-Mobili.html), Configure section, Physical Location step. Checked 2026-09-25.
[^34]: In Cisco TAC's troubleshooting walkthrough, the roaming device pool was not selected because the Physical Location was set to None, and checking Physical Location is a listed troubleshooting step. Source: [Configure and Troubleshoot Device Mobility](https://www.cisco.com/c/en/us/support/docs/unified-communications/unified-communications-manager-callmanager/211535-Configure-and-Troubleshoot-Device-Mobili.html), Troubleshoot section, Physical Location verification step. Checked 2026-09-25.
[^35]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Prerequisites. Checked 2026-09-25.
[^36]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview. Checked 2026-09-25.
[^37]: Because Region is roaming-sensitive, a roaming phone's codec and bit-rate selection follows the region of the roaming device pool (inferred). Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, roaming-sensitive settings list. Checked 2026-09-25.
[^38]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Configure a Device Pool for Device Mobility. Checked 2026-09-25.
[^39]: When a phone returns to its home location, Unified CM removes the roaming device pool, downloads the home configuration and resets the device. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview. Checked 2026-09-25.
[^40]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, roaming-sensitive settings list. Checked 2026-09-25.
[^41]: If more than one device pool is associated with the matching subnet, Unified CM assigns the roaming device pool round-robin. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, device pool assignment scenarios. Checked 2026-09-25.
[^42]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, device mobility groups (Richardson to Boulder example); Device Mobility Interactions table, Roaming row. Checked 2026-09-25.
[^43]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, device pool assignment scenarios. Checked 2026-09-25.
[^44]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, device pool assignment scenarios. Checked 2026-09-25.
[^45]: 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). Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Overview, roaming-sensitive settings list. Checked 2026-09-25.
[^46]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), Device Mobility Configuration Task Flow. Checked 2026-09-25.
[^47]: 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. Source: [Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Device Mobility](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), View Roaming Device Pool Parameters. Checked 2026-09-25.