Methods and apparatus for dialing numbers using a session initial protocol device are disclosed. According to one aspect of the present invention, a method includes obtaining at least a first part of an input string associated with a dialplan. The input string includes at least one character. The method also includes determining if at least a first potential target string stored in a local cache includes the first part of the input string, and accessing an external call manager arrangement if the first potential target string stored in the local cache does not include the first part of the input string.