The UK's only environmental telephone company, Green Mobile, has issued a Tree Challenge, promising to plant three trees for each new phone contract registered with it.

Green Mobile donates 4 per cent of business customers' on-going phone bills to conservation charity the Woodland Trust, in order to plant trees.

It works out that one tree is planted for every £125 spent on your phone bill and three trees are planted for each new mobile phone contract.

For information call 0845 233 0000.