Which parameter must be set for the end user for Jabber for Windows or Mac to register successfully with Cisco Unified Communications Manager in softphone mode?

Jabber in softphone mode relies on the primary extension field of the end user account to resolve which directory number and associated CSF device to use for SIP registration with CUCM. Without this value, the client cannot determine the correct line to present and registration fails. This setting directly links the user identity to the DN required for soft-client call control.

Group membership governs feature permissions and access controls but is not evaluated during the Jabber SIP registration process with CUCM.

Subscribe Calling Search Space controls which devices a user can monitor via Busy Lamp Field subscriptions and has no effect on softphone registration.

Remote destination profiles are used for Mobile Connect single number reach functionality and are not involved in Jabber softphone registration.

Device association links a device to a user account but does not alone satisfy registration - without the primary extension set, Jabber cannot identify which DN to use in softphone mode.