So if 4G is cranked so that these phones pick it over 2/3G, their owners will not be able to make calls? That's going to go down well. I suppose by then most will be out of contract.

No different in the USA either, similar problem with 4G/LTE and 3G/CMDA or 3G/UMTS on older handsets.

As long as 2G or 3G coverage is on a similar (or better) frequency there should be no issue, the only problem is for EE if they use 800 and the 2G is on 1800. This could be why EE will only use 800 in rural areas.

I read that there are some Samsung devices (S3 LTE i guess) that use the same Qualcomm modem as the iPhone 5/5c/5s but there is an operator firmware that enables VoLTE somewhere in the world.

I read another rumour that Apple doesn't flash the firmware in the modem chip in the 'field' as there is too high a chance of permanently bricking the device. That would make a lot of sense.

Sounds like a clusterfuke to me. Better stick with 900 2G for calls then.

Stay with O2 or Voda then. Orange was very popular in business for reliable calls and used 1800 for 2G since 1994 launch.

VoLTE will be switchable on the phone - on& off

My family in the USA report volte works and clearer calls are great, but no downside. They've had since Christmas.

But what if you have a 4G phone which can't do VoLTE? You can't turn it off because it's not there. The networks have to hold back 4G so that those people don't pick up a 4G signal over 2/3G. Innit?

I think it'll depend on the network but on Three and Voda I think you'll be able to make calls with intouch and voda's app.

This is all guesswork so far from this forum. We are assuming 4G will be held back. What if the networks don't bother? And assume its only a very few areas where 4G signals get indoors that have no 2G - and that those areas could use WiFi calling?