What is the purpose of Mobile and Remote Access (MRA) in the Cisco UCM architecture?

MRA is used to access Webex cloud services only if authenticated with on-premises LDAP service.

MRA is used to make secure PSTN calls by Cisco UCM only while on-premises authentication.

MRA is used to make B2B calls through Expressway registration.

MRA is used to access the collaboration services offered by Cisco UCM from off-premises network connections