unable to text to internation numbers
I have an iPhone 6. I have SMS on, imessage on, MMS on. I can text fine in the US and receive texts from international numbers but am unable to send SMS text messages to international numbers. I can use imessage internationally. I cannot use sms I have used 011-421-xxx-yyyy' +011-421-xxx-yyyy, +421-xxx-yyyy all unsuccessfully. I've recycled the phone. What am I doing wrong?
iPhone 6, iOS 8.1.3