What is a Touch Tone Phone?
A touch tone phone, also known as a multi-frequency (MF) telephone, is a type of telephone that uses a keypad to input digits. Unlike the older pulse dialing system, which sent a series of on-off tones, touch tone phones use a combination of different frequencies to represent each digit. This technology has been widely adopted and has become the standard for modern telephony.
How Does a Touch Tone Phone Work?
When you press a digit on a touch tone phone, the keypad sends a combination of two different frequencies to represent that digit. For example, the number 1 is represented by a 941 Hz tone followed by a 1336 Hz tone, while the number 2 is represented by a 697 Hz tone followed by a 1209 Hz tone. This process is repeated for each digit, and the combination of tones is what the phone company’s equipment uses to identify the number you are dialing.
Here’s a table showing the frequency combinations for each digit:
| Number | Frequency 1 (Hz) | Frequency 2 (Hz) |
|---|---|---|
| 0 | 941 | 1336 |
| 1 | 941 | 1336 |
| 2 | 697 | 1209 |
| 3 | 697 | 1336 |
| 4 | 697 | 1477 |
| 5 | 770 | 1209 |
| 6 | 770 | 1336 |
| 7 | 770 | 1477 |
| 8 | 852 | 1336 |
| 9 | 852 | 1477 |
These tones are sent to the phone company’s central office, where they are decoded and used to route the call to the desired destination. The touch tone system is more reliable than pulse dialing, as it is less susceptible to noise and interference.
History of Touch Tone Phones
The concept of touch tone dialing was developed by Bell Telephone Laboratories in the 1960s. The first touch tone phones were introduced to the public in 1963, and they quickly gained popularity. By the early 1980s, touch tone phones had become the standard for residential telephones in the United States.
One of the key factors in the adoption of touch tone phones was the introduction of the rotary dial phone. While rotary dial phones were widely used, they were prone to errors and were slow to dial. Touch tone phones, on the other hand, were faster and more reliable, making them a more attractive option for consumers.
Features of Touch Tone Phones
Touch tone phones offer several features that make them more convenient and efficient than pulse dialing phones. Some of these features include:
- Speed Dialing: You can program your phone to dial a number with a single button press, making it easier to call frequently used numbers.
- Redial: If you hang up and remember the number you just called, you can press a button to redial it.
- Caller ID: Touch tone phones can display the caller’s name and number on the screen, making it easier to identify incoming calls.
- Voicemail: Many touch tone phones have voicemail capabilities, allowing you to receive and manage your voicemail messages directly from your phone.
