If you experience problems with the Dial by Name function (i.e. you're trying to locate a user, but get no matches), make sure that the entry you're looking for actually exists as a Calling Line ID Last Name or Calling Line ID First Name.
Dial by Name searches Caller ID fields rather than user's first or last names. So if you have a user "John Smith" with caller ID name of "Sales 1", searching Dial by Name for "John Smith" will not produce any results, but searching for "Sales" will.