Simon had a short lifespan, partly because it was so far ahead of its time

At 1lb (0.5kg), it weighed the same as a bag of sugar and cost $899 (£539)

It will go on display as part of a exhibition at London's Science Museum

Tomorrow marks the anniversary of when the Simon first went on sal e

At 20 years of age, IBM's Simon is considered a relic, already long consigned to the past.

But, clunky as it may be by modern standards, the device has an important place in history - it was the world's very first smartphone.

Tomorrow marks the anniversary of when the Simon first went on sale, and in October it will get a new lease of life as part of a permanent exhibition at London's Science Museum.

Charlotte Connelly of the Science Museum in London holds a IBM Simon mobile phone from 20 years ago, which was the first ever smartphone and the forerunner to today's mobiles. IBM said it was called Simon because it was simple and could do almost anything you wanted

The phone was developed by firm IBM and the American cellular company BellSouth. IBM said it was called Simon because it was simple and could do almost anything you wanted.

Charlotte Connelly, the content developer for the exhibition, said it was initially marketed around the idea of the game 'Simon says'.

'The marketing was that it was so simple, that it could do anything you instructed it to,' she explained.

Compared to today's smartphones it was incredibly basic, but in 1994 it was far ahead of its time.

The Simon, with its green LCD screen, had a stylus with touchscreen technology.

An original IBM Simon Personal Communicator is placed next to an Apple iPhone 4s. August 16 marks the 20th anniversary of the world's first smartphone, the IBM Simon, going on public sale. It has been described as a forerunner to Apple's range of phones

FEATURES OF THE FIRST EVER SMARTPHONE: SIMON The Simon, with its green LCD screen, had a stylus with touch screen technology. At 1lb (0.5kg), it weighed the same as a bag of sugar. Available only in the US, it initially cost $899 (£539) when it first came out. Users could write notes, draw, update their calendar and contacts and send and receive faxes, as well as allowing calls. It even had a slot for cartridges that were primitive 'apps'. The battery lasted only an hour on talk mode and it didn't have mobile internet. Advertisement

Software allowed users to write notes, draw, update their calendar and contacts, and send and receive faxes, as well as allowing calls.

It even had a slot for cartridges that were primitive 'apps'.

But at around nine inches long (23cm) it was also about half the size of a house brick. It had an aerial and its battery lasted just an hour when making phone calls.

It also weighed the same as half a bag of sugar.

'It was half a kilogram (1lb) - you wouldn't want to carry it too far,' Ms Connelly said.

Nevertheless it was revolutionary, combining for the first time attributes of PDAs, with mobile phone technology.

'The Simon was the first device that took these two items and put them together in a single package,' Ms Connelly said.

'It could do all the things in a PDA and it also had fax capabilities and could do email, though it had to be synched to a computer to do that.

'That is why we are calling it the first smartphone, even though that phrase first came along much later.

'It has all the components of a smartphone, including a slot in the bottom to insert different applications, such as mapping ones, spreadsheets and games.

'So it was really a forerunner to the iPhone.'

The Simon, with its green LCD screen, had a stylus with touchscreen technology. At 1lb (0.5kg), it weighed the same as a bag of sugar. Available only in the US, it initially cost $899 (£539) when it first came out

Available only in the US, it initially cost $899 (£539). Around 50,000 handsets were sold, primarily to business people.

The one owned by the Science Museum was bought on eBay for an undisclosed sum.

'I asked the seller what it was for and it was owned by a project manager for a construction firm,' Ms Connelly said.

'He really liked the fact that his co-workers could fax him technical drawings, he could sign them off while on assignment and send them back to them, rather than having to have papers all over the country.'

But the Simon was to have a short lifespan, partly because it was so far ahead of its time.

Ms Connelly said: 'It didn't make a massive splash. It was only available in the States, and was only marketed there as well.

'It was just early adopters that knew about it at the time - it wasn't something that everybody in the country craved to have.

'There was probably an element of lack of demand of people not buying into it, but it was only a few years later that the Nokia 9000 Communicator came along.'

The Motorola Transportable communicator from 1985 is shown on the left, the IBM Simon mobile from 1994 is in the centre and the modern day Fairphone 2014 is on the right

The price was dropped to $599 (£358) after six months because it was commercially unsuccessful, before it was withdrawn completely. Not many are left in circulation now after IBM recalled it.

'First of all it was very expensive,' Ms Connelly said as she explained its failure.

'Secondly, the battery only lasted an hour in talk mode, so it wasn't very practical, and third there was no mobile internet.

'A lot of the things we want our mobile phone to do today just weren't possible because the connectivity wasn't there.'

She added: 'It has got all the fundamental things there, but honestly, would I like to carry it around in my pocket? No, I wouldn't. You can see the potential but it didn't really deliver.

'But really it was a brilliant idea that was just a bit ahead of the technology.

'All the bits of the jigsaw puzzle weren't quite in place. It was too far ahead of its time.'

But while it is already a relic, most handsets now probably lost in dusty garages or forgotten in bottom drawers, the IBM Simon left an indelible mark on the world of mobile technology.

'It is the first smartphone,' Ms Connelly said. 'It is the first time these crucial components were brought together in one single device, and although it wasn't a commercial success it was a pioneer.'

Simon will be exhibited at Information Age: Six Networks That Changed Our World at London's Science Museum on October 25.