This thread is going round in circles, the facts are clear,
I suggest we quote this post if we get the same questions:
800MHz + VoLTE (Super-Voice) launched on the 10th of September and covers 50% of the population for indoor coverage. It's currently only working with the Galaxy S5 and the LG G4 (they must be running Three software, so either the phones are supplied by Three or you manually flashed Three's ROM onto them). There are other devices that will be made compatible in the coming months when Three rolls out software updates to them. They must be running Three software (other than the iPhone).
FAQ:
I have a phone that supports 800MHz+VoLTE, will it work on Super-Voice?
The internal list of supported phones is
here. All of those dates are subject to change. Your phone MUST be running Three software. If you bought it from another network and unlocked it, or you bought it unbranded, it will not work unless you flash Three's ROM onto it OR you have an iPhone.
Why won't it work if it's not running Three software? Why does the iPhone work?
There is no way for Three to add the VoLTE settings into your device without a software update. If it's not running Three software, they cannot push an update to your device, it can't get the VoLTE configuration, it won't work. This is a limitation of Android and possibly also Windows Phone, but not of iPhones. iPhones work in such a way that Apple is in control of software updates, Three submit the VoLTE configuration to Apple and then Apple pushes it as a carrier update to all iPhones regardless of where they were purchased.
I don't care about VoLTE I just want to use 800MHz.
You can't use 800MHz without VoLTE. If you could, you may be in a situation where you would have signal but not be able to place a phone call, this would cause all sorts of chaos for Three in terms of customer complaints from people who don't understand, so Three made the decision to only allow VoLTE+800MHz or nothing.
I have a Tablet/MiFi that supports 800MHz, can I use it?
According to Three, you should be able to as you can't place phone calls on these devices there's no reason to block them. I've seen posts of this not working though, I'd contact Three about that as it should work.
What about the Nexus 6?
For some odd reason, the Nexus 6 is able to access 800MHz but not use VoLTE. This is very much an exception to the rule. It is not on Three's list, and Three don't sell the phone. It might be a possibility for Google to update the Nexus 6 ROM to add Three VoLTE support as they have done in the USA with carriers but don't get your hopes up. As for why it can access 800MHz, no one knows why, it shouldn't be able to according to Three. I wouldn't count on it continuing to work forever. Whenever I get on 800MHz now with my Nexus 6 I'm kicked off pretty promptly anyway.
How do I check device support and 800 coverage?
On the
Three coverage checker, enter your postcode and in the box below enter your device. You will be shown the coverage for your area and device. If you want to double check that Super-Voice is in your area, enter the Galaxy S5 as your device and it will show Super-Voice coverage if available. If your device doesn't show Super-Voice coverage but the S5 does, your device isn't currently compatible. If your device does show Super-Voice coverage but it doesn't work, you need to be running Three branded software. The coverage checker is always updating so keep an eye out.
Does VoLTE work over 1800MHz
No, not currently. You must be on 800MHz to use VoLTE.
Has 1800MHz power been increased since the launch of 800MHz
No, as it's the same situation as before. If the power was increased you could potentially be in a situation where you cannot place phone calls.
What about *devicename*, I can't find any information about it?
If it's running Three software & supports 800MHz+VoLTE I don't see why it wouldn't be made compatible eventually. GSM Arena is a good website to check if it supports 800MHz, you're looking for Band 20 support. VoLTE support is harder to find out about, but in general I'd say most devices from the last year are good to go, you can also Google your devicename + volte and see if it has support in other countries. If it's not running Three software and you can't make it run Three software, it's not compatible.
I'll add more if I think of any. If you spot any errors, let me know!