Phone number not available for iMessage
I have an iPhone 5. I went on holidays and used a new SIM card while I was away. When I returned home I put my original SIM card back in my phone. Now when I send iMessages or use facetime it goes through my email address. I checked my iMessage settings and my email is selected and then my holiday phone number is blanked out. My phone number doesn't even appear.
I am definitely connected to my carrier as I can use data, send texts, make calls, etc.
How do I get my phone number to be an option?
iPhone 5, iOS 8.3