Cannot send texts from iMessage to sprint users (from Verizon)
For some reason I cannot send messages via iMessage to any of my contacts who use Sprint. I'm on Verizon if that matters. I talked to an Apple Rep on the phone and they thought maybe sprint users had to have use an email address instead of a phone number, but I cannot find any such thing online.
All the rest of my contacts work fine in iMessage. Sadly my immediate family is all on Sprint. Included an image of what I get when I try (the white space is the 10-digit phone number).
iPhone 5, iOS 6.0.2