Where does an IP phone obtain the extension number and speed-dial settings from?

A.
the settings that are configured on the physical phone

B.
the registration file that the phone receives from the Cisco Unified Communications Manager

C.
the device and line configuration in Cisco Unified Communications Manager, during the
registration process

D.
the default device profile that is configured in Cisco Unified Communications, Manager

Explanation:
When we configure IP phone profile in CUCM that time we also configure extension number and
speed dial as per requirement.
When IP reachability gets establish between IP phone and CUCM then phone will download config
file from CUCM during initial registration process.
Link: http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/3_1_2/ccmcfg/b06phone.html