I use an iPhone 6 on EE in the UK and in the last year (And more so since EE introduced wifi calling) the signal and call dropouts has been shocking. I have complained to EE on numerous occasions, you get the usual "we are upgrading our masts, the mast near to you is under investigation" etc bla bla. I was eventually put onto a techie chap who had sympathy with me and he explained that there is no international standard with phone signals. If phone A shows 3 bars signal strength, then phone B might show only one bar. He said not to get hung up on it, as long as it makes calls, forget what it shows. Well I explained that is my problem, dropped calls and the phone going straight to voicemail, I don't even get the opportunity to answer it!! After many an hour on the phone EE have refunded one months phone bill and given me £10 a month off my bill for the next 6 months, I think the guy knew I was not going away with the problem. I have been an Orange/EE customer since Adam was a lad and I seriously suggested I would be leaving the network, hence a bit of credit for me, I certainly think they are pushing 4G data to the detriment of what mobile companies core business is, to allow you to make mobile phone calls!!