Almon Brown Strowger, and the Evolution of the Rotary Phone

By Sam Gibbs on at

When Almon Brown Strowger discovered that his undertaker's business was tanking thanks to a rather cheeky ploy from a phone operator who was directing his calls to his competitors, he decided enough was enough. The user should be the one who decided who they were calling, not the operator. The automatic telephone exchange and the rotary phone was born.

From its inception, before being largely retired back in the 1980s, the rotary phone in Britain went through quite a few iterations. Back then, no one actually bought phones; they were instead rented from the General Post Office (GPO), which had a monopoly on the telephone up until 1982. Here's how Strowger's little lightning-bolt of an idea was adapted over the years...


The GPO 100 Series

The first rotary phones to be introduced in Britain were the GPO 100 series. These were crude wooden things, which quickly evolved into the exquisite Type 150 introduced around 1929. The classic candlestick phone, as seen in various period shows like Poirot, didn't actually contain any of the electrical workings, which were all confined to the wooden box mounted behind it.


The GPO 200 Series 

The 100 series was shortly followed up by an all-together more modern-looking contraption. The Type 200 series was introduced in 1934 and remained in production right up until 1957. It was the first to combine the receiver and transmitter into one handset, called the Tele 232 Handset Micro Telephone, creating the traditional phone-shape we know and love today. Like the 150 before it, it was an empty box that hooked up to a separate external bell, which could be screwed onto the bottom if needed.


The GPO 300 Series

The Type 300 series was introduced in 1937, bringing with it integration of the bell set, and was available in various specific models with different qualities of finish and extension capabilities for around the home.


The GPO 700 Series

We can thank the Americans for the introduction of the next evolution of the rotary phone, with the Type 700 series. It was the public's demand for a more modern-looking phone, like those featured in American TV shows, that forced the GPO's hand. It was released back in 1959, in various two-tone colours. The 706 brought with it an electrical circuit board and the first variable regulator for sensitivity, which reduced interference from radios, like those fitted in taxis at the time.


The Trimphone 

The 700 series then morphed into something decidedly retro-futuristic in looks, with the 722 Trimphone, which was introduced in the late '60s. It was a premium telephone at the time, with subscribers having to pay more for that particular design. It came with new-style wiring; a high impedance ringer, and became standard issue in late 1971.

After the introduction of the Trimphone, true rotary dial phones began to die out. The 700 series models were updated with push-button dial pads, even though their actual dialers were still based on the old impulse, loop-disconnect system and not the more modern touchtone or DTMF dialling system that took over in the 1980s.

In 1981, the GPO, or Post Office Telecommunications as the phone department was then called, was abolished in favour of the separate British Telecommunications corporation, spun off from the Post Office. The evolution of the GPO Telecoms into BT brought with it the death knell for rotary pulse dialling, heralding a brave new world of touch-tone dialling in the UK. However, if it hadn't been for Almon Brown Strowger and his rotary telephone, the phone explosion we benefit from today might never have happened.

Image credits: Wikipedia, Shutterstock

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