Last morning I received an SMS from T-mobile (my current provider) stating that if I restarted my phone set I would see EE instead of T-mobile as a signal provider. I did the restart and was able to see EE instead of T-Mobile at the top of the screen. All fine and well. Problem started when I wanted to make a phone call. I was getting disconnected right away. I went to the nearest T-mobile centre (Barnet Spires Mall), and the very helpful lady there was able to solve the issue. Apparently Everything-Everywhere is having problem with its 3G network because of 4G network work. The lady set my phone to get the 3G network from a manually selected list (when searching for available list two EE options came, she selected the bottom one). The phone started working. As I normally use the mobile only for phone calls I asked her is it better to change signal to 2G (GMS instead of UMTS). She said that was also worth a try. I changed my signal type to 2G. This was also working fine. During this rollover period for 4G I think this problem will go on for some time.