T-Mobile today announced its new Just SIM service. The new initiative lets you hold on to your old handset and, as the name suggests, sign up to a new SIM-only deal.

In a bid to make people care more about the environment and hold on to their handsets longer, the Just SIM service tariff promises to be cheaper than a standard 18-month contract tie-in.

Flexible mobile contract

Anytime, any network UK calls are priced at 30p per minute, while anytime, any network SMS text messages cost 10p. You'll get free SMS text messages and free voice minutes thrown in too. You can leave the service at any point, giving 30 days' notice.

"We're rewarding people who provide their own handsets with minutes and texts. With no long-term contract, Just SIM is an intermediate option between pay-as-you-go and longer contracts and gives customers the freedom to choose a new handset and a longer contract when they're ready," said Phil Barden, director of consumer business at T-Mobile.

Three price plans are available for £20, £30 and £40 per month, available now.