KEYPAD PHONES

Telephones with keys instead of a rotary dial became available in the 1970s. Early phones would still rely on pulse dialling, later versions have a switch to select between pulse and tone dialling where modern ones are tone dialling only. These days the distinction between telephones and computers is blurred where many people use smart phones and they communicate via internet using social media.

Telephone companies are moving towards VoIP (Voice over Internet Protocol),  phasing out POTS (Plain Old Telephone Service). This will have a significant impact on the reliability of telecommunication systems. Modern networks will stop working when there is a powercut. The old telephone network relied on 48 volt battery banks in the exchange building that would keep communication channels open in the dark.