The WWF is the latest organisation to launch its own branded MVNO with the promise of donating 10 per cent of call revenues to conservation. The charity has partnered with Cognatel and Digital Spring Mobile using Vodafones network to offer SIM-only deals on Wildlife Mobile. Digital Spring is said to be taking less profit than it usually would in order to ensure call rates remain competitive.

A 10 minute call could pay for six tree seedlings to help restore critical areas of tiger habitat. Two weeks of regular usage, the organisation said, covers the costs of a three-person anti-poaching patrol to protect tigers and rhinos in Nepal. Its target is for customers to make 2m minutes of calls by the end of 2013.

“Most people use a mobile phone, so this is an innovative and easy way for people to do their bit for conservation. If you’re passionate about the environment and wildlife, it won’t cost you anything to raise vital funds for WWF while you use your phone,” WWF’s communications and fundraising director, Tobin Aldrich, said.

WWF says that Wildlife Mobile wont cost more than other major networks to use – and, in some cases, works out better – with pay-as-you-go rates 30 per cent cheaper. Bolt-on data can be bought as an extra. Pre-pay monthly bundles start with the Penguin at £9.50 per month for 200 minutes and 500 texts. The cheapest package with mobile internet is Penguin + Data at £15.50 for 500 MB. The top package, Rhino + Data, is £37 for 1600 minutes, 2500 texts and 1GB of internet.

You dont sign a contract so you have to renew your bundle each month. All of these packages come with free Wildlife minutes for people to call their green-minded friends.