The first of six "Solarbox" was unveiled on Tottenham Court Road this week.
    
The service is free to use although users will be shown adverts as they wait for their phone to charge.
    
Many of the UK's red telephone boxes have largely fallen into disuse.

The boxes have had a makeover recently - painted green and fitted with a roof-mounted 86cm solar panel.
    
Inside there are a variety of charging stations for different models of phone and a screen which shows advertisements.
    
The advertising screen is reinforced to deter vandals and the boxes are maintained daily and locked overnight.
    
The project was the brainchild of two geography students turned entrepreneurs Harold Craston and Kirsty Kenny in response to a competition run by the Mayor of London.
    
Both studied at the London School of Economics (LSE) and were interested in finding new ways to use public spaces.
    
"I lived next to a phone box in my second year at uni and walked past it every day. I thought, 'There are 8,000 of these lying unused in London and we must be able to find a use for them,'" Craston was quoted as saying by the BBC.
    
The solarbox can charge up to 100 phones a day, offering a 20 per cent battery boost in 10 minutes.
    
Since launch, about six people per hour use the booth, according to the founder.
    
"On launch day, my phone ran out of battery and I genuinely had to use the box," Craston said.
    
The kiosk funds itself by advertising. Its inventors say the costs to run the machine are low -- it requires only basic maintenance such as cleaning, and initial costs of installing each Solarbox is forecast to be recouped within three months.