Refer to the exhibit.
A Cisco Unified Communications Manager Extension Mobility enabled user attempts to log in to a new phone where Cisco Extension Mobility Cross Cluster Service is configured with the URL that is displayed in the exhibit. The service is configured on a Cisco Unified CM 9.X or later Unified CM cluster. After the user enters the user ID and PIN, the phone displays "Login is Unavailable (23)." Which configuration requirement supports Cisco EMCC and avoids this error condition?
A. The device must be subscribed to Cisco EMCC Services.
B. The given user ID is not found in the remote cluster.
C. The user must associate a device profile.
D. The Cisco IP Phone Services configuration for Cisco EMCC must set the enterprise subscription.
Answer is B.
https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/9_0_1/ccmfeat/CUCM_BK_CEF0C471_00_cucm-features-services-guide-90/CUCM_BK_CEF0C471_00_cucm-features-and-services-guide_chapter_01011.pdf
My initial thought was that you’re wrong since the User ID does not need to be configured in the remote cluster for EMCC to work but in this case the remote cluster is actually the user’s home cluster. So yes, the answer is B.