HKLM\SYSTEM\CurrentControlSet\Services\AtmUni\
The AtmUni subkey stores configuration data for the Asynchronous Transfer Mode (ATM) user-to-network interface (UNI) Call Manager. The ATM UNI Call Manager is a Windows 2000 service that creates switched and permanent virtual circuits for ATM signaling and communication.
The Parameters subkey of AtmUni stores entries that apply to all ATM network adapters.
In addition to these entries, the Parameters subkey contains an Adapters subkey which contains a subkey for each ATM network adapter installed on the system. The subkeys within AtmUni\Parameters\Adapters are named by the GUID of a particular network adapter and store entries that apply only to that adapter.