The service, delivery etc were excellent but I encountered what I consider to be a serious problem. I wanted to transfer the number on my existing phone to my new phone but could not find any mention on the website on how to do this. I would assume that nowadays most people have an existing number that they wish to transfer so it is difficult to understand this omission. At the very least you should have an up-to-date phone number to call (which was not the case on O2's website) and a link to the website of the service provider. An explanation of the process and how long it should take would also help.