Are you on PAYG or pay-monthly? PAYG is auto-enabled for roaming, providing you've used your phone in the UK first.
Pay-monthly customers who have already left the UK, should login to myEE online or app, and navigate to parental & data controls. Check the following 2 options are enabled: "International roaming" & "Call abroad & premium rate"
If, for whatever reason, you can't enable the options - you will need to contact EE C/S via webchat, another working phone or a web-calling app over a WiFi connection.
