• Enable by default
• To auto assign DN
• All DN must be of the same type either single or dual-line but not mix
• The type if not specified will catch all
• cfw provide the Call Forward Busy Number and timeout value

telephony-service
  auto-reg-ephone
  auto assign <start-dn-tag> to <end-dn-tag> [type phone-type] [cfw <number> timeout <seconds>]

• The DN needs to be defined as well

ephone-dn <start-dn-tag> dual-line
  number 1000
...
ephone-dn <end-dn-tag> dual-line
  number 1999

• To show all auto registration attempt

Router# show ephone attempted-registration