Except Tesco who allow you all your data whilst roaming in the EU even unlimited contract subject to fair use of two months in every four although some of us have done three months with no issues, but it must be used in the UK as well. The Tesco sim is a phone sim and will not work in home routers but will work in some mifi devices, there is a list of compatible devices on their website however my mifi is not listed as compatible but still works okay, I believe Tesco allow you a two week trial period in which it can be returned if it doesn't work in your device, in addition you must manually enter the Tesco APN or else it is unlikely to work or work reliably.all of them had a monthly limit of about 25gb when in Europe