Not able to make a phone call but can txt

Hi AngiBro_1097143 👋
Have you checked if your handsets are compatible with the SMARTY network?
https://help.smarty.co.uk/en/articles/8985136-checking-if-your-device-is-4g-volte-compatible

I had the same problem with regards to a Samsung Galaxy phone that had the ability to connect to VoLTE but didn't have the option to do so and so I posted this.....
https://community.smarty.co.uk/t5/chats-hacks/can-t-make-receive-calls-not-necessarily-a-network-problem/m-p/28408#M18064
If you don't see 'LTE' (rather than 4G) under 'Mobile Networks/Network Mode' then you won't be able to connect to the '4G' network.

I moved to iD Mobile (uses the 'Three' network the same as SMARTY) as they had my handset on their 'Approved' list and yet I had the same problem.
https://www.idmobile.co.uk/help-and-advice/approved-handsets

I saw that others had the same problem (with a SG phone), so this is a more comprehensive answer for 'what to check for and how to remedy it' 
https://community.idmobile.co.uk/ask%2Da%2Dquestion%2D18/just%2Dsome%2Dbasic%2Dquestions%2Dabout%2Dnew%2Dsim%2Dcard%2Dvolte%2Dupgrade%2D68606

 I'm afraid I can't help with regards to the Sony Experia as I don't have experience with that model but 'Google' (other search engines are available) is your friend! Again, you may need to see 'LTE' rather than '4G' in the network connection settings to connect to the network.

I hope you find the answers! x

AngiBro_1097143  There is a very complex thread that covers this problem in HUGE detail. If you are a 'techie' then you may be able to follow the steps and get your phone to work - if not, a local phone shop may be able to help for a fee.

It looks like the 3G turn-off is sparking problems with a lot of phones.