Cant make calls or recieve calls only works on whats app

[SR333]

I recently have been abroad and purchased an esim which I downloaded to my phone Now back in UK and have disabled the esim but my phone will not now make or receive calls other than by whats app 

[bristolian]

WhatsApp is just an internet app - all this proves is that your phone has a working internet connection, which can just as easily be WiFi.

What happens when you try making a call? Does your phone show a mobile network connection? Can you send & receive text messages?