Couldn't find it on support.avaya.com. Further research indicates it may be discontinued. I have limited experience on Avaya DECT. I was burnt too badly back in the day by the NEC Drover PHSs and Kirk deployments that were never commissioned to have confidence in the technology. But Avaya do it pretty well.
I suspect that maybe one of your bases stations has been dedicated as the 'OM' which may now be called ADMM. Try browsing to your base stations on the network.
See below for the information I found from the linked document on page 11.
Avaya DECT Mobility Manager Mode
In this mode, an IP Base Station functions as a regular IP Base Station. Additionally, it is responsible for
H.323 signalling between the IP DECT system, IP Office and a web management interface.
To designate a IP Base Station as the ADMM, assign an IP address to the IP Base Station DHCP
settings (see Avaya IP DECT Startup) or set the data via OM Configurator (see Static Local
Configuration of the IP DECT). If an IP Base Station is designated as the ADMM, it starts extra services
(for example, the Web Service to support the management interface).
Note
• It is possible to deactivate the DECT part of a IP Base Station. If the DECT Interface is
deactivated then the resources (CPU and memory) are available for the ADMM.
Note
• Avaya Power Over Ethernet adaptors (type 1151) are non-802.3af compliant, and therefore
cannot power the ADMM.
Avaya IP DECT Mobility Manager
The Avaya IP DECT Mobility Manager (ADMM) performs the following tasks:
• Signalling gateway (H.323 <-> DECT GAP).
• Media stream management.
• Manages synch over air functions between IP Base Stations.
• Facilitates system configuration modifications.
• Provides additional services, for example:
• Directory (LDAP or TFTP based).
• WML browser.
The ADMM must run on one of the IP Base Stations.
Maybe also try this:
Avaya WinPDM Software
Depending on the URI configuration the ICR can be completely ignored.
If your URI is configured to use internal data then the IP Office will look into the user's SIP tab and if you have *'s it will look into ICR.
A madman with a taste for speed.