Hi,
youve probable solved your issue by now but if not
I was having the exact same problem , the fix that i found worked for me was under the ephone set "type 7942" and restart the phone
config t
ephone 1
type 7942
i would also delete from telephony-service the following line
telephony-service
directory last-name-first
and any manual entries you have added
reason i say this is because i found that leaving in these lines somehow only allowed the phone to find manually entered names & numbers, taking out the lines allowed my phone to automatically find all names & numbers assigned to an ephone