iMessage not working to friend in another country
Hello! I need help. I have my phone set up correctly to send and receive iMessages from my phone number and my apple ID. I know that my friend also has hers set up the same way. I live in Texas, USA and she lives in London, England. We can not figure out why iMessage isn't working. I have tried everything I know, so I hope somebody else has an idea. Thank you in advance for your help. We both have iPhone 5S's with the most recent iOS update(7.1.2 I believe)
iPhone 5s, iOS 7.1.2