Help Not Registered on Network - with Full Reception

[rikmayall]

Since yesterday evening:

I can't make incoming/outgoing calls or send receive SMS on my phone. Interestingly there is about a 5 second window right after I turn on/off Airplane mode I can send/receive SMS and make a phonecall - the phonecall will last as long as I want, but when I hang up I'm back to square one!
I have no data connectivity
I can connect to WiFi etc.
I have full reception i.e. full bars
My phone is not blacklisted (I checked IMEI with network operator)
Other SIM card won't work on my phone
My SIM card works on another phone
When I go into settings to select mobile network I am 'Unable to connect. Try later'

Any help or suggestions anyone? Haven't made any significant changes since yesterday (think I updated Facebook and YouTube)

 

[Digital Controller]

First off welcome to the forums!

Have you tried resetting the APN settings?

 

[rikmayall]

First off welcome to the forums!

Have you tried resetting the APN settings?

Ha, how rude of me, hello!

Yeah tried that there, same story...

 

[rikmayall]

It actually turned out phone was blocked by network provider even though they said it wasn't. Got a replacement (it was bought in an exchange shop)​