Trilogy Communications is the first consumer PR agency to work on the site, which collects consumers' surplus mobile phones in return for cash - some of which is donated to charity.
The phones are then sent on to be used in developing countries rather than being thrown away.
Envirofone.com, launched in March 2006, is planning a publicity drive to convince the public that there is no catch to the scheme.
Trilogy has been briefed to target consumer and lifestyle press with a campaign showing how the concept works. The agency will push the message that people can donate to a charity of their choice and be rewarded with cash or vouchers in return for an unwanted mobile phone.
The company estimates there to be up to 100 million unused mobile phones in the UK, worth a total of more than £1.5m.
Eazyphone Group CEO Pete Petrondas said the scheme had witnessed ‘huge growth' and ‘the time was right to call in specialist PR support'.
The group has already launched envirofone.com in Ireland and Holland and plans to expand into countries such as France, Spain and Italy later this year.
The account was won after a pitch last year (PRWeek.com, 19 December 2006). Pendry White's corporate comms brief is unaffected.