With a new set of 3G tariffs, T-Mobile has fallen into line with other UK 3G providers and agreed to allow Internet telephony on its network - at a price.

Tariffs unveiled last week include a premium rate that allows VoIP (voice over Internet Protocol), though subject, like T-Mobile's other rates, to a monthly usage cap. Previously, T-Mobile banned any use of its 3G network for VoIP sessions, citing quality and commercial concerns.

T-Mobile now offers two "Web 'n' walk" packages for laptop data cards. Web 'n' Walk Plus costs £29 per month for "unlimited" Internet access, and includes a pass for accessing WiFi hotspots. VoIP is banned and "unlimited" usage means 3GB of data per month.

Web 'n' Walk Max, at £44 per month, offers a slightly more liberal interpretation of "unlimited" Internet access, raising the actual limit to 10GB per month. It also allows VoIP and includes a hotspot pass.

Every other UK 3G operator allows VoIP, and 3 UK has a promotion deal around the Skype VoIP client. Interestingly, 3, Vodafone and O2 all have caps of 1GB on data transfers.

3 offers three tariffs: £20 per month for 100MB of data, which doesn't include the £49.99 data card; £30 per month for 256MB; or £45 per month for 1GB.

Vodafone offers a 250MB 3G package for £25 per month, plus £99 for the data card. "Unlimited" data (which imposes a "fair use" cap of 1GB per month) can be had for £45 per month, and there's also a Vodafone Data Travel plan that includes "unlimited" domestic data and 100MB of international transfers for £95 per month.

O2 offers six UK data plans, ranging from Data 5, which offers 5MB for £8 per month, to O2 Data Max 1024, for £45 per month, which offers "unlimited" data. O2's fair usage policy places a 1024MB limit on average monthly usage for the Data Max plan.