Introduction: Rotary Dial Speed Dial

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Today I made a simple hack that made my day. It only took me 5 minutes and I wanted to share it with you.

Recently, I had to use the old Rotary Dial phone because my modern electronic land line phone malfunctioned.

Although it seems stylish , you can imagine how boring to dial a number of 10 digits or more with that old rotary phone and then need to just press Redial , and you cannot !!

So I thought today of this simple idea and it worked.

Can I use the DTMF dialer on my smart mobile phone to make calls faster?

That is what I came up with .....

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Step 1: Technical Background

The old rotary dial phone uses the pulse dial system. It uses ON/OFF voltage signaling for numbers encoding.

One ----- > Encoded with ON pulse

Two ----- > Encoded with ON OFF ON pulses

Three ----- > Encoded with ON OFF ON OFF ON pulses

And so on until

Zero ------ > Encoded with Ten ONs and OFF in between

On the other hand , Tone system phones use the DTMF( Dual Tone Multiple Frequency ) systems which encodes each digit with the summation signal of two frequencies corresponding to a frequency table resembles the Tone phones Keyboard layout.

You can read more on Wikipedia :

The tones ( sounds ) generated in tone phones and decoded by the land line central switch to meaningful numbers. And also the old pulse numbering systems is decoded into numbers.

In some Land Line Phone networks , the two systems are supported for backward compatibility with old phones.

So , the machines in the network central office is ready to hear both signals. It only depends on the signals your phone generates.

So I thought I could generate DTMF tones using my mobile phone using the Dial Pad or the Phone Book to make my life easier, and it worked.

Step 2: Setup and Finalize

All you need is :

The old rotary dial phone ( I assume you already have and want to make your life easier while living with it )

Your mobile phone.

- Put the mobile phone speaker next to the land line phone Microphone for better sound transfer.

- On the mobile phone dial pad , press the digits for the number you need to call.

- Just don't press anything else.

That's all.

You can see that it works and the number you need to call on the land line phone is dialed successfully and ring tone is heard on the land line speaker.

I 've tried it today and it worked excellent. I actually placed a call to a number I wanted to call.

Note :

To call a number from your phone book , you need to install a program on your Mobile phone that accesses the phone book and makes the DTMF tones corresponding to these number.

I just searched Google Play Store for " DTMF Dialer " and I found an app that makes this job.

That's it . I hope it was a useful instructable and you can try it and work with you.


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