In which situation would an administrator configure telephony services, but not configure any
individual ephones?

A.
Phones that are controlled by Cisco Unified Communications Manager Express

B.
Cisco Unified Communications Manager SRST fallback

C.
Cisco Unified Communications Manager Express with HSRP

D.
Remotely located phones that are controlled by a third-party PBX

E.
This is not a valid scenario. Ephones are always required.

Explanation:
When a phone registers for SRST service with a Cisco Router and the router
discovers that the phone was configured with a specific extension number, the router searches for
an existing prebuilt ephone-dn with that extension number and then assigns that ephone-dn
number to the phone. If there is no prebuilt ephone-dn with that extension number, the system
automatically creates one. In this way, extensions without prebuilt configurations are automatically
populated with extension numbers and features as the numbers and features are “learned” by the
Cisco router in SRST mode when the phone registers to the router after a WAN link fails.
http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/admin/configuration/guide/cmesrst.html