Are you on contract or PAYG? Did you use that SIM for making calls or texts in UK before you left to go abroad?
If you are on contract, did you activate roaming on your EE a/c before you left UK by texting ROAMING to 150? Having a roaming add-on doesn't of itself activate roaming on your a/c.
Often just rebooting the phone is the simple remedy. Also try selecting a network manually rather than auto. Otherwise login to your MyEE account online & go to Menu > Account Settings > Parental and Data Controls > Roaming Abroad and also Call Abroad and Premium Rate. They will show as ticked if roaming and calling abroad is activated. If not ticked, can you activate these settings?
If you can't enable the Roaming Abroad and the Call Abroad & Premium Rate settings of your online MyEE, you will need to call CS. Try calling CS on the Freephone no. in my sig. via Skype over WiFi. It should be free.
PAYG is auto enabled for roaming as long as you've used the SIM in the UK previously. You won't see any of those settings & don't need to change anything.
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To phone EE CS: Dial Freephone +44 800 079 8586 - Option 1 for Mobile Phone & Mobile Broadband or Option 2 for Home Broadband & Home Phone
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