Most mobile phones are equipped with the facility to compose your own dial tone tune. Simply install the tune E A D G B E (or several tunes to suit whichever instruments you play). Check the tones against an authentic tuner and hey presto, you have a guitar tuner by simply listening to your own dial tone. Unfortunately MY phone does not have the "compose" facility. Does anybody know of a "tune" website that includes guitar tuning in its downloads.