Mobile phone users are tantalisingly close to the day when they can power up any phone with the same charger.
But industry players gathered at the the World Mobile Congress in Barcelona still have some way to go.
Three years ago, 17 manufacturers and operators agreed at this same conference to share the same standard for mobile phone chargers fitting into a micro-USB socket.
The relatively modest goal, defined by the global industry's GSM Association, was that most mobile phones sold in 2012 should be compatible with the new universal charger.
Despite European Union pressure on the industry to ensure all phones share the same type of charger and thus avoid hassle for users and vast amounts of unnecessary waste, results have been mixed.
"It has been announced so many times and the customers are still waiting for it," sighed Flavio Cuchietti, one of the project's supervisers at the UN agency, the International Telecommunication Union.
"It has been clearly aimed at smartphones, which account for about 25-30 percent of the market in Europe. Then what about the other 70 percent, and what about the Third World?" he asked.
The ITU in 2011 asked all manufacturers to share the same mobile phone charger by 2014.
Last year, a study by the University of Genoa researchers found 10 different charger models among the eight major market players.
"Our intention is not to punish an industry or to block their development. Our intention is to find a solution that is viable, adding extra complexity and extra cost, but in the end we get to a universal solution," Cuchietti said.
The result is also less waste, he said, estimating that more than 100,000 tonnes of chargers were discarded every year by consumers when they bought new phones.
But despite uneven progress, manufacturers say they are optimistic.
Samsung and Sony Mobile say all their models now use the universal micro-USB charger while Nokia estimates that about 70 percent of mobiles sold in the second half of 2011 were compatible with the new standard.
ITU secretary general Hamadoun Touri said the universal charger provided practical benefits for the customer. For example, people who forget their chargers when travelling would easily find a spare.
"I would like to see this technology extended across the world so that when you buy a new telephone that charger is just an option," Touri said.
But that would require manufacturers to take another bold step.
"Consumer expectation is to have a charger included with the sales package," said Peter Harrison, in charge of regulatory standards at the Finnish phone maker Nokia.
"We are now in a transition period," he said.
Bertrand Villie, in charge of sustainable development at Sony Mobile France, said manufacturers were reluctant to stop selling the charger along with the phone unless everyone agreed to do so at the same time.
"We cannot decide on our own to sell our products without a charger; if we did that no-one would buy Sony Mobile!" he said. "Even so, the mobile phone industry is the only one in the world that has agreed on a universal charger."
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