Q: Issues with iPhone 5 ringing home

I wonder if someone can help! I'm cabin crew and have been trying to use my iPhone 5 and ring home to the uk and keep getting sorry this function is not available! My phone is in flight safe mode till we land and when I ask the phone to search for signal I get no service so have to manually look for a network and select. I can place and receive text messages with no issue just the calls won't work. Spoken to my network provider EE and they say I have no restrictions on the account and should be receiving and making calls because I receive and places text messages! Any help on what is wrong with my phone?

Tim