I can confirm VOLTE works for me even though there are no arrows shown.

I live in a strong 2100, 1800 and 800Mhz area. I was connected to 4G 1800Mhz and when I made my first call it switched to 3G.

And a few seconds later when I made my second call it switched to 4G 800Mhz and it remained on it through out the duration of the call.

At the end of the call it switched back to 4G 1800Mhz.

I have taken a couple of screenshots which I will upload later.

did you have to force your phone on to band 20? i thought it would not go to Band 20 if you have 3G signal.

Nope, I didn't expect it to switch to band 20 but it did.

Also I am getting a lot of network retry messages since the last few days when checking emails etc.

It's interesting because I had a similar experience on the M1. I went from 1800MHz to 800MHz for a good 2-3mins before back on 1800MHz and this was an area with strong 2100/1800MHz signal. The phone was also network idle.

Breaks through walls my arse sat in the outlaws now super pumped area and the signal is exactly the same none existent ee you have a new customer incoming

EE use the same frequencies as Three so I don't think you're going to see much of an improvement unless you have an old Orange mast nearby...

I've noticed my phone switching to 800MHz occasionally at home when it has a poor (but still usable, sort-of) 3G signal.

Perhaps the priority isn't 0 as we first thought?

I noticed this at work too the other day, had 2 bars of 3G and it changed up to 800 every so often. They may have adjusted the priority for all we know.

EE 2G could be running at significantly higher power levels than Three 4G, not to mention there are a lot more EE 4G masts around than Three ones.

Well I'm done waiting for Three to improve. Super-Voice has been launched, the coverage map shows excellent coverage indoors, in fact it's showing almost blanket indoor coverage of my entire town, yet still I am unable to get signal indoors in the same places as usual. (iPhone 6S Plus iOS 9.2, Carrier 23.1)

Contacted Three support, they told me yes these areas should have Excellent 4G Super-Voice coverage and they will investigate for me. They call me back a week later and tell me that unfortunately these areas are poor signal areas and I was actually asked "what would you like us to do about it?". When I told them I'm just going by their own coverage map, I hoped that Super-Voice would give me coverage in places where I previously didn't have coverage, I was told that I had been connected to their super-voice network and it's working as it should (I have been connected to Super-Voice, one time when I first updated my iPhone and it rebooted, it rebooted onto Super-Voice, that's it). They seem to make up excuses just to close the support ticket.

I tell them no it isn't working and they say there's nothing they can do. I ask them if the local site has Super-Voice activated and they tell me yes and it's working as it should. I know for a fact it's not broadcasting Super-Voice, it doesn't even have 800 capable antennas. Super-Voice is coming from far away and the coverage map is an absolute lie.

I don't feel like Three is going to improve any time soon. EE does a much better job with speeds and especially coverage around here so, I will switch to the 20GB BT Mobile plan for £25pm unless anyone else has any better ideas?

I am in the same position with my S6 & my S4.
The map shows blanket coverage of a strong signal but yet, I have many occasions without a signal.
3 UK are blatant liars.

I will be leaving them as soon as my contract is up. If money was no object, I would challenge them in court to end my contract now with no penalty because they are unable to provide me with a regular service at my home address.

When EE flicks the switch on 800 and VoLTE, for a fair time there isn't going to be anyone that can compete.

Three will still be cheaper though, at least for now. And Feel at Home, despite blocking many services, is still going to be quite enticing until such time that EU roaming charges is no longer an issue.

Feel at home is great for the regular traveller, some of my family are and they have Three data contract SIMs in their 4G tablets. EE SIMs in their phones, and use the tablets more when abroad.

As tourist WiFi is in a lot more places when you leave western europe (perhaps something to do with our legal system), finding WiFi is generally easy, say in the USA.

Feel at home is great for a lot of things, but when you've got a 3 year old who wants to watch YouTube or Netflix it's useless as they're blocked.

I also wanted to watch someone for work on Vimeo and that was also blocked.

Sure, a certain VPN can get around their restrictions, but it's annoying even if it is free. I can't even pay to access these services!

I would really question how high power 3's 800MHz is. I'm about 4mi away from the nearest EE 4G 1800 mast which also carries 3 1800 and 800MHz. 3's 800MHz is only maybe 5dBm stronger than the EE 4G signal.

Three's implementation of VoLTE is downright bizarre... and isn't doing them any favours it seems.

They'll probably turn it up in areas where the 800 enabled mast density is higher, so to not swamp a mast - Even with the low priority. I noticed this with the single 800 enabled mast in my area as it doesn't actually cover that larger area and the signal strength isn't much stronger than 1800, i predict that they'll turn up the power on it when the other mast in the town gets enabled which according to Three CS will be within the next couple of months.

Forgetting the radio propogation differences of 800/1800, every 3db change is a doubling or halving of signal strength I believe...

I look forward to them enabling VoLTE on 1800 as hopefully they'll turn up the power on it, that said the 800 in the area is fairly reliable if i force it. 800 for Three is no winner when it comes to speed and their 1800 seems to perform pretty well on the single enabled mast most of the time.

Correct. But that does not have a similarly significant affect on distance or data speeds. E.g. +3dB does not double the propagation distance.

Frequency will likely have a much greater impact depending upon the environment/situation.

My understanding is that...
Low frequencies tend to favour distance and handle (pass around) some obstacles better.

High frequencies can make better use of reflections and multipathing to improve signal quality, maintain signal where low frequencies would fail. They can also penetrate certain materials more effectively.

It's very subjective. One of the regulars mentioned that high frequencies are better at passing through window appertures and can therefore service inside buildings that have thermal insulation in the walls (that block/interfere with RF) better than low frequencies.

Which means that the best providers will have high cell density and a broad range of different frequencies.

Many would consider EE to be in or moving towards this position.

Three (with the purchase of o2) could manage this and so could Vodafone. Both need serious investment to catch up to EE though.

Yes - sometimes its worth having a Voda/o2/ee SIM instead and paying the best roaming deal. (As you've blogged already!)

and this is why Orange and one2one at 2G / 1800 still managed a very good coverage despite Vodafone and Cellnet using 2G / 900, back in the 1990s. Then Orange went and built over double the masts to ensure indoor coverage was good. (Which helped dramatically for 3G).

Increasing the transmission power of a base station may increase your received signal level by a few dB, but that does not automatically mean you will be able to use your mobile in places you couldn't before.

The transmission power of your mobile is very low, and fixed. This means the usable coverage area is limited by the ability of the base station to receive the signal from your mobile, not by the ability of your mobile to receive the signal from the base station. This is called uplink limited.

If an uplink from your mobile cannot be established, then your mobile will not be registered and will show no signal even though you are receiving a strong signal from the base station. Your mobile might be receiving the high powered transmission from the base station, but that does not mean the base station is received the low powered transmission from your mobile.

In situations where the coverage area of base stations overlap, increasing the transmission power of the base station can actually degrade usage coverage because interference levels increase.

In most cases, increasing the usable coverage area is achieved by upgrading the base station receivers to newer versions with better sensitivity, by using higher gain antennas (and adjusting the tilt), and by using mast head amplifiers to boost the signal received from your mobile. This explains why the 2G/3G coverage footprint often increases after a base station antennas and receivers are upgraded to support 4G.

The frequency also make a difference as 800Mhz exhibits very different propagation characteristics to 2100Mhz, although each has it's own pro's and con's.

I'm pointing this out because people often focus exclusively on the transmission power of the base station, without realising that it's not the only factor that affects usable coverage, and often the limiting factor is the low output power of their mobile.

Good few posts of late...
Radio is very interesting, lol.
Don't forget the receiving antennas on the sites are upto 2 metres tall - slightly bigger than your phones unless you're Dom Jolly.
Think power is definitely important, but with same frequencies being used over & over, interference and the cleanliness of the 'pilot' channel is very important to a tiny phone - imagine being in a small pub with 10 people all talking simultaneously loudly, tuning into your mate can be difficult.
More so, atmospherics will play a part as well - remember foreign tv (in UHF band, 800 anyone) leaking in during various weather systems now and again.
As well, Orange did tackle their 1800 limitations head on, instead of hand-ringing and listening to unimaginative accountants (Voda last 10 years??) they decided correctly to build out a dense plus rural (again no VO2) network and grew spectacularly because they saw a future in mobile or a do or die future maybe, being new(ish).
Finally, I think we can thank the Germans (DT anyway) for making EE a modern network in partnering with 3 - and actually seeing mobile data as (again) the future and not a novelty (that we can blagg our way through, sorry Vo2 you missed that again)!
My only concern is now the lack of competition forming in the sector, meaning higher prices for less, we shall see...??

That may be so but 1800 on both Three and EE is on significantly reduced power to stop it over-reaching 3G. 1800 being lower and 4G being much more robust means power has to be wound right back.
Since my mast came on, sat outside in the car with the phone in a holder I normally get 3 bars EDGE now.
Atmospherics have to allow EDGE to be bordering 4 bars before 4G appears at 1-2 bars.
This means that when EE (for example) reach the tipping point of having enough users on 4G voice and can change CSFB to 2G, that 4G signal is going to be there all the time at 3-4 bars and I won't see 3G again.

Gareth and yourself are also correct here in stating that while your phone only has a tiny receiving antenna, the signal is being broadcast at a high power (in comparison) and conversely while the phone is only pumping out 1 Watt over again, a tiny antenna, this signal is being listened too by new modern super sensitive massive great panel antennas.

There are plenty of places here where my iPhone could easily get a 4G1800 signal to a mast but isn't actually picking up a strong enough incoming signal at the moment to actually show 4G.
I'm such a massively sad anorak that I know which mast my signal is coming from most of the time and it's particularly easy here as it's like middle earth (unless you are on a hill you are normally only in line of, or near line of sight of one mast at a time.)

In fact ordinarily I don't think anyone here would be taking about transmission power if it wasn't blatantly obvious when 4G launched that is was greatly power restricted.