Phone Tones

Date:    Tue, 14 Apr 1998 18:41:13 -0700
From:    Michael Seery 
Subject: Re: sound effects help

>I am working on a project using several types of phones.  I need sound
>effects for specific things like the tone for each number on the keypad.  I
>also need each sound for each number of a rotary phone.  Any help finding
>these resources would be greatly appreciated.

Here are frequency pairs for North American phones (from the alt.2600 FAQ):

25. What are the DTMF frequencies?

DTMF stands for Dual Tone Multi Frequency. These are the tones you get when you press a key on your telephone touchpad. The tone of the button is the sum of the column and row tones. The ABCD keys do not exist on standard telephones.

         1209 1336 1477 1633
     697   1    2    3    A
     770   4    5    6    B
     852   7    8    9    C
     941   *    0    #    D

Type                Hz          On      Off
---------------------------------------------------------------------
Dial Tone         350 & 440     ---     ---
Busy Signal       480 & 620     0.5     0.5
Toll Congestion   480 & 620     0.2     0.3
Ringback (Normal) 440 & 480     2.0     4.0
Ringback (PBX)    440 & 480     1.5     4.5
Reorder (Local)   480 & 620     3.0     2.0
Invalid Number    200 & 400
Hang Up Warning 1400 & 2060     0.1     0.1
Hang Up         2450 & 2600     ---     ---