With the Multi-Device Access (MDA) feature, you can register more than one SIP device with a single extension.
MDA for a CC endpoint
Device Adapter does not support Multi Device Access (MDA) for a CC phone with Avaya Aura® Call Center Elite.
Avaya Aura® Call Center Elite does not support MDA because after you log in to an extension with your agent ID, you cannot register at any other extension using the same agent ID. Your registration to the extension is exclusive in Avaya Aura® Call Center Elite.
If you are logged in to an extension and if you try to log in to another device, then Avaya Aura® Call Center Elite clears the registration of the already registered device and registers the new device.