Helensburgh Puzzles #20 - Words II Mystery Cache

Helensburgh Puzzles is a series of puzzle caches placed around of the suburbs of Helensburgh, Stanwell Tops and Otford. There are 36 puzzle caches in total, placed in the shape of a puzzle piece. The puzzles are of varying difficulty to encourage to learn about puzzles, codes and how to solve them.

For planning purposes, please see the the Helensburgh Puzzles website.

Do you want to show how old you are? Just tell me which of these phones you've used. All could be used for calling other people and to send messages. All you need to do is just use the letters on the rotary dialpad...

To locate GZ, solve the following puzzle:

7777666888440844777333303336668877708933555888330366680333444888330
77774449907777444990332777780666663303334443338999033344433389990 664446633033344488833077773388833660664446633