I am thinking of moving to o2 pay monthly sim only, mostly to get o2 TU Go, as all networks have dead spots in my house. I have given up waiting for EE WiFi calling - as it looks like it will not be available on sim only, even if I use a EE firmware pay as you go mobile.
I have googled o2 TU Go and read the reviews on Google Play - but I am still slightly confused by it. Is it possible to ask the forum for a few answers?
Do text messages appear in my normal Android text messages area?
If not, how does the phone alert me to texts?
Am I right in saying that to make and receive phone calls over WiFI, I will have to use the app dialer, not my normal phone dialer?
What happens if I do try to make a call using my normal phone dialer? Does the app somehow turn the normal phone off?
Is the app overall reliable? Are there many missed/straight to voicemail calls?
Many thanks for any help.

You could try the O2 forums.

http://community.o2.co.uk/t5/TU-Go/bd-p/555

Personally I was with O2. Their signal here is poor and I was going to leave. They launched TU Go and I tried it for a few months. It was better than the dodgy mobile reception but I found there were too many annoyances. IIRC being unable to sync contacts or turn off voicemail were two. Things may have improved now but I jumped ship.

--
Pete Forman
http://petef.22web.org/payg.html

I have work colleagues who have all deleted the app as unreliable. Good idea in theory. Three have an app called "Three in Touch" which is apparently only a little bit more reliable.

I now have about 4 customers using it that I am aware of (as they asked me to set it up).
It seems to work fine for a while and then suddenly starts playing up.
Not really monitored it properly but they all complain it isn't that reliable.

I have been using TUgo for well over a year now, and i find it excellent. My phone would be useless without this app,as reception is so bad as my home has a granite front.
When making calls it flags up "how do you want to make the call" and just click on tugo or phone,very easy.
messages come through on tugo via wifi with a distinct sound, and then ,much later in my home, in the usual messages.

it is very simple to use ,and I have it installed on my tablet, as well as my phone.

I do see some people getting on with it well but the general feedback is not good I think.
Having to make sure the app is running would be a pain as I like to regularly clean-up background apps and I'm bound to close that one in my haste
The main issue for me though in my busy work life would be having two sets of call logs and messages.
I spend half my life in those two and it's not fast enough as it is. I would very quickly tire of having to remember which app the message was in.

EE WiFi calling is now live and I have to say I was sceptical it would be any good.
Well EE have totally delivered this time and I can't believe how good it is.
It's possible EE will bring it to PAYG at some point.
Also Vodafone are getting WiFi calling in the summer apparently and they may do PAYG from the start.

Actually of all the other networks, it's only Vodafone who seem to be doing anything positive to catch up to EE while O2 make stupid comments like "It's good to see EE following our lead (TuGo) with WiFi calling" When in fact it was Orange who first had any kind of WC in 2006 with UMA (Signal Boost).

Three just seem to have stopped doing anything while they wait to see if they can buy O2, probably to stop them making daft comments like that!! Hahahahaha

Yes, I concur, its amazingly good. I helped a friend upgrade a 5c today and then we made some test calls in HD Voice which hadn't worked in the house before (indoors mostly 2G/4G signal, 3G by window).

So I've seen it now working with 5c, 5s, 6 iPhones, with full contract, and SIM only contract accounts. Suspect not PAYG.