DTMF Phone Demo

Demonstrates the Dual Tone Multi-Frequency sounds used by telephones. Includes dial tone, ringing and busy signals.

RANDOMIZE TIMER PRINT PRINT " Phone Dialer" PRINT PRINT " +---------+" PRINT " | 1 2 3 A |" PRINT " | 4 5 6 B |" PRINT " | 7 8 9 C |" PRINT " | * 0 # D |" PRINT " +---------+" PRINT " Use comma for 1 second delay" DO LOCATE 15, 20: PRINT SPACE$(60); LOCATE 15, 20: LINE INPUT "Enter a number to dial: ", dialed$ IF LEN(dialed$) = 0 THEN EXIT DO PlayTone 350, 440, 4 FOR d = 1 TO LEN(dialed$) dial$ = MID$(dialed$, d, 1) SELECT EVERYCASE dial$ CASE "1", "4", "7", "*": left = 1209 CASE "2", "5", "8", "0": left = 1336 CASE "3", "6", "9", "#": left = 1477 CASE "A", "B", "C", "D": left = 1633 CASE ",": left = 0: rite = 0: _DELAY 1 CASE "1", "2", "3", "A": rite = 697 CASE "4", "5", "6", "B": rite = 770 CASE "7", "8", "9", "C": rite = 852 CASE "*", "0", "#", "D": rite = 941 CASE ELSE: left = 0: rite = 0 END SELECT IF left THEN PlayTone left, rite, .25 NEXT rand = INT(RND * 2) 'random sounds after dial FOR i = 1 TO 4 IF rand = 1 THEN _DELAY 3: PlayTone 440, 480, 1 'ringing sound ELSE: _DELAY .6: PlayTone 480, 620, .3 'busy signal END IF NEXT LOOP END SUB PlayTone (FREQ1, FREQ2, Seconds) Pi2 = 8 * ATN(1) '2 * pi Amplitude = .5 'amplitude of the signal from -1.0 to 1.0 SampleRate = _SNDRATE 'sets the sample rate FRate1 = FREQ1 / SampleRate FRate2 = FREQ2 / SampleRate FOR Duration = 0 TO Seconds * SampleRate 'play 5 seconds left = Amplitude * SIN(Pi2 * Duration * FRate1) 'sine wave rite = Amplitude * SIN(Pi2 * Duration * FRate2) 'LOCATE 1, 1: PRINT left, rite _SNDRAW left, rite NEXT DO: LOOP WHILE _SNDRAWLEN END SUB

Code by Ted Weissgerber

Note

Use comma to pause for one second between numbers dialed. Can use special * codes too!

See also

• _SNDRAW
• SOUND
• PLAY

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