Can't send SMS text messages from my iPhone 5S to SOME non-iPhone mobile numbers
Since I got my iPhone 5S in February 2014 I have been unable to text SOME of my friends who are non-iphone users with different providers like AT&T, Verizon, etc. I have Verizon. I send text message after text message, get my green bubbles, even get a date and time sent, but my friends never receive my messages. These friends can text me normally, but I can't even text a reply back when I receive their messages. I've been to the Verizon store and they tried a few things but basically said, sorry. I guess it's their phones. Really???
My phone seems to be the common denominator. Can anyone help?
Thank,
Robin
iPhone 5s, iOS 7.1.2