Changed to O2 last week and have not been able to use the phone away from the house WiFi as signal is a joke. Most of the time it shows emergency calls only and the download speed is a shocking 0.1Mb/s on 4g, I kid you not. This was whilst standing in front on the 5g mast whilst only receiving 4g on a 5g phone. Customer service is shocking, had to wait 30mins each time to get through with no help whatsoever, they even promised to phone me back to resolve problem but never did. Ended up going to local O2 shop to get it resolved, there was a queue of 6 people in front of me even before shop had opened, all complaining about the same joke of a network service. When I was seen I was told the mast cannot deal with the volume of people using it, I live in a holiday town so basically I have to wait till the winter to get a decent signal! JOKE OF A SERVICE PROVIDER. AVOID.