I was getting a great signal with o2sim card but because a have bt broadband a decided to get a bit sim the problem is if am in my own house a don't get a signal at all every body trying to phone me can't if am in house or in anywhere but if a go out side it works and there can't be a problem with my broadband as it works my now and fire TV help please
Could activate wifi calling, usually rock solid on most devices. May need to disable 4g calling / VoLTE if you use android.
otherwise you have a 30 day money back period with BT SIM cards so could cancel without paying.