A UN report this week showed that more than half the global population now pay to use one.
The survey, by the International Telecommunications Union (ITU), an agency of the UN, also found that nearly a quarter of the world's 6.7 billion people use the internet.
But it is the breathtaking growth of cellular technology that is doing more to change society, particularly in developing countries where a lack of effective communications infrastructure has traditionally been one of the biggest obstacles to economic growth.
By the end of last year there were an estimated 4.1bn mobile subscriptions, up from 1bn in 2002. That represents six in 10 of the world's population, although it is hard to make a precise calculation about how many people actually use mobile phones.
Africa is the continent with the fastest growth, where penetration has soared from just one in 50 people at the turn of the century to 28%.
Much of the take-up is thought to have been driven by money transfer services that allow people without bank accounts to send money speedily and safely by text messages, which the recipient - typically a family member - can cash in at the other end. Vodafone's M-Pesa money transfer service was launched in Kenya in 2007 and now has 5 million users.
The ITU report points to the Gambia, where mobile subscriptions have rocketed amid stiff competition among mobile operators. Out of almost a million telephone subscribers, there are more than 800,000 mobile subscriptions but only about 50,000 fixed telephone lines in service.
Developing countries now account for about two-thirds of the mobile phones in use, compared with less than half of subscriptions in 2002.
The adoption of mobile technology has outstripped the growth of fixed-line connections, which rose from 1bn to 1.3bn over the same period, with market penetration stuck just below 20% for some years.
The figures demonstrate that many people in the developing world are bypassing the older technology altogether.
In the developed world, many people use more than one mobile device, with subscriptions exceeding population by 11% in Europe.
On the other hand, a single mobile phone may have several users in poorer countries, where handsets are sometimes shared or rented out by their owners.
The report also recorded a marked increase in internet use, which more than doubled from 11% of people using the net in 2002 to 23% last year.
Here the report identified a clear gap between the rich and poor world: fewer than one in 20 Africans went online in 2007, for instance, and less than 15% in Asia, whereas Europe and the Americas recorded penetration of 43% and 44% respectively.
Across the world just 5% of people have broadband internet at home, although this rises to 20% in the developed world.
Sweden was the world's most advanced country in the use of information and communications technology, in an index of 154 countries that took various factors into account such as access to computers and literacy levels.
South Korea and Denmark were placed second and third in the list, while the UK was ranked 10th.
Mobile phones have changed Congo irrevocably, especially Goma. The country has only about 20,000 land lines after the system collapsed under Mobutu Sese Seko's ruinous dictatorship.
Now traders shipping imports to distant towns, farmers sending produce to the main cities, and those involved in the thriving gold and diamond smuggling trade use their phones to check prices, text quotes and arrange deliveries. Women who once sold roasted corn by the roadside now make a living dealing in mobile top-up cards and recharging flat phone batteries in a town where much of the population doesn't have electricity.
"Everyone but the very poor has a cell phone," said Mukeba. "Even the guy who only makes a few dollars a day picking up passengers on his bike. Even the woman selling things by the roadside. Almost everyone finds the money."
Cell phones have helped transform Goma in other ways. The town's economic boom of recent years has been fuelled by war and plunder, particularly of the rich mines in eastern Congo. Among them are diamonds and gold but also coltan, a rare but crucial element in mobile phones.
The small fortunes to be made by mining it sent tens of thousands digging for black mud and attracted criminal syndicates and foreign armies. "It all came at once," said Mukeba. "War, cell phones, dollars. Some people are getting very, very rich and everyone is making a little bit of money."
Nortel has offered to give fired employees early access to pension plans and provide medical benefits to retirees under the condition that they drop their claims for severance pay in bankruptcy court. 
Wireless 20/20, for instance, used to be WiMAX 20/20, but now its on the LTE bandwagon.
