Telephone MF Tones


This is only of historical interest but de rigueur for a website.

700900110013001500
9001
110023
1300456
15007890
1700KPKP2ST

And of course there is the tandem frequency of 2600 Hz.

1209133614771633
697123A
770456B
852789C
941*0#D

Note that these frequencies are in a step of approximately exp(0.1).