But the make and model can be extracted from the IMEI.
They could use this to filter them.
Also firmware as well.
If IMEI model = S5 and firmware = Three then allow.

If you're speaking specifically about 800mhz and not VOLTE.
I'm currently in the process of trying to get VOLTE enabled on a note 3 (which is not ever going to be supported by 3) by modifying firmware files.
I have got as far as managing to connect to the 800mhz 4g signal. Surely therefore they cannot be restricting by IMEI because I definitely shouldn't be able to connect with my note 3 at all.
I'm continuing my work to see if I can get VOLTE functional.

Well done for getting 800 data!

I've put a PAYG MBB SIM in a E5372 Mi-Fi but don't know if I'm on 800 or not. Signal seems no better than it would be with 1800.

Good point.
I will shut up.
Now I come to think of it RAN Man said there are several ways they can filter devices.
Can't remember what they were now.

I can't get on to 800MHz even with a mobile broadband SIM in a mifi device that 3 thinks is capable (the map changes to the 800 one when you type it in)

Interesting reading on here over the last few days. Seems some people who should be able to get 800mhz data can't, and other people who shouldn't, can! It's all a right mess isn't it? Although I accept my note 5 will never be officially supported, I do now hold out some hope of at least being able to connect to the 800mhz frequency at some point. Having said that, I'm not all that convinced that this small amount of 800mhz is the panacea that I'm thinking it will be. In fact, I can't really complain about the network at all really, especially in terms of coverage, which for me is great. Although occasionally it slows down, this is quite rare. I have been thinking about switching, but have to be careful as the grass isn't always greener!

Don't forget that if the device gets even a sniff of 3G, it won't even consider going on to 800. It's seems to be setup like 2G is on other networks, a last resort signal.

I've got a pair of 860 MHz analogue headphones and they go nuts when it tries to connect to 800.

I can force it to 800MHz 4G only, doing so means getting no service. Setting it to its default connects it to 3G

My unlocked Samsung j5 with my 3 sim card was recieving 3/3+/4G for the last 5 months and switching between them constantly but all this last week its been on 4G constantly so Im presuming my nearby mast has been adjusted?

Just done a speedometer check on it and it was reading 24 bits download so that's up from 5-8

Interesting, I have this phone too. My area is very poor and my signal comes from Oranges old 2G mast so full signal but no data. Can't win

I can force my Mi-Fi to 4G only (and have) but not a specific band.

At least not via the standard interface, as there may be AT commands to do it - but that's a bit too much bother.

I have a few times had my device been on very low signal 3G (and not be losing signal) and switch to 800MHz so I'm not sure if the priorities thing is completely accurate?

I'm watching your posts with interest as if you can work out all the settings/files needed then anyone can 'update' whatever phone they have and that annoying Three is a great incentive to do it!

It's probably very little that needs changing.

Clearly Android has the ability to let people update settings over the air, without needing to have specific firmware, but for some reason nobody is using it yet.

It should mean that any Lollipop or Marshmallow phone should be easily configured to work with VoLTE, and indeed Wi-Fi calling.

There must be loads of networks all over the world wanting to ramp up their 4G power, and needing VoLTE to do so, so it's quite amazing it's not happening. It's not just down to Three, or EE or any other individual operator.

The range on 800MHz truly is astonishing.

The 800MHz signal in my house that just will not die (literally works everywhere) at -120dBm down to -125dBm is from a mast at least 20 miles away.

I'm amazed that the techno-bods out there haven't already seen what the important settings are and/or extra files are and posted it up for all. It's on some popular phones and so it would only take someone who knows about such things having a look to see what the changes are.

Perhaps you have said this if so apologies, but how did you get it onto the 800Mhz signal, if you don't mind sharing of course.

Has anyone here done the LG G4 Three modification? Does the phone automatically switch to 800MHz with it or does it have to be forced.

Got a text today stating that Shrewsbury was about to be activated for Super Voice - but didn't say when. Strange considering coverage checker says it already is and my device (not sure if it's a 6 or 6S on 3's systems) isn't yet supported!

The coverage checker is normally way behind reality not in front of it. My town got Three's 1800mhz 4G on Oct 24 for 4 days then off for 4 days and then back on permanently, but the coverage checker didn't show it till weeks later. Not a bad signal for 1800mhz as I even get 1 to 2 bars inside my house where I normally sit. (Who needs Super-pumping? )

My LG G4 switches to 800 No problem.

Was this originally from Three though or one you modded?

Originally from 3, I got the updates straight away when I got the phone a few weeks ago.

When I put my postcode into the Three coverage checker it's saying:

"We're planning some network improvements in your area on 30 November 2015. We're really sorry if this affects your services. It's crucial work that will improve your network experience."

Does this mean 4G might be on it's way? The mast is 3G only at the moment.