It took the mobile industry almost 20 years to win its first 500 million subscriptions worldwide - but only seven more years to turn that number into three billion. Key to that uptake has been the evolution of handset design. Here, telecoms.com takes a look at some of the landmark devices from the last 26 years.

1981

The first mobile network, based on the NMT-450 (Nordic Mobile Telephony) standard, launched in Sweden and Norway in August 1981. Nokia, now the world's biggest handset vendor, but then a rubber and cable manufacturer, released the first 'mobile' phone - the Mobira Senator 450 - through a partnership with Finnish television maker Salora. Perhaps 'mobile' was a touch misleading, though - the unit weighed in at nearly 10 kilos.

1986

By March of 1986, mobile telephony - still based on NMT - had spread throughout the rest of Scandinavia and notched up its first one million subscribers. Nokia, in a nod to its later success, met the opportunity with the introduction of the first handheld NMT phone - the Mobira Cityman.

1990

By July of 1990 it was becoming clear that mobile telephony had a bright future. Truly portable devices, although not yet pocket sized, were driving uptake - and ten million subscribers had signed up for the service. Pictured here, the MCT200 from Japanese manufacturer Murata is one such handheld device. But it would not be until 1991, when the first GSM network was launched by Radiolinja in Finland, that mobile telephony would begin to be seen as having true mass market potential.

1996

By April 1996, GSM had delivered mobile telephony to the masses, and over 100 million people had subscribed to cellular services worldwide. US handset manufacturer Motorola also hit upon a design that was to be repeated time and time again by handset manufacturers in years to come (and especially by Motorola), with the release of the iconic StarTAC clamshell phone.

2000

Four years later and the global mobile subscriber base had quintupled to 500 million users. Mobile phones were smaller and more affordable. Nokia managed to shrink the handset down to truly pocket sized dimensions with the 8260, as well as removing the external antenna.

2002

By the February of 2002, the global mobile subscriber base had doubled yet again and the first billion milestone was achieved. Mobile telephony was evolving rapidly and PDA (Personal Digital Assistant) vendors such as Research In Motion (RIM) and Palm were beginning to see opportunities in adding cellular capabilities to their devices. RIM released the BlackBerry 5810 on an unsuspecting public, allowing them to access email anytime and anywhere. It proved an addictive service, eventually spawning the term 'crackberry'.

2005

It only took three more years for the world's mobile user base to double yet again, reaching the significant milestone of two billion subscriptions in September 2005. By this stage, many developed markets were beginning to mature, and competition was becoming exceptionally fierce in Western Europe. Handset design had taken another leap and the mobile phone was fast becoming a fashion accessory, with Motorola taking a new twist on an old design with the release of the popular RAZR V3c.

2007

Another two years, another billion subscribers. By July of 2007, there were three billon subscriptions - close to half the world's population. But, while emerging markets were delivering much of the solid growth, developed countries were already looking towards a future of mobile internet-enabled gadgets. Voice revenues were falling and operators were increasingly looking to mobile data and content to bump up their sales. Apple shook the entire industry with the release of the iPhone, which set the bar for handset designs in the months to come.