This is actually a pretty annoying issue. (Score 1)

My girlfriend switched to a Nexus 4 from an iPhone shortly after the push of iOS 7, and came at me with the old: "This Android is a piece of shit! It won't receive texts!". I went through quite a lot of head-scratching trying to figure this out, as I initially assumed it was a problem with her new provider. After about 20 troubleshooting steps with little help from Apple or the internet, I figured out that only people with iOS 7 devices weren't able to send her texts. The solution: iOS7 leaves SMS off for iOS contacts by default. She had to "unregister" her iPhone and remove her mobile number from their database, letting Apple's iMessage servers know to always default to SMS with her phone number. This, of course, took nearly a week to kick in, in which her boss and co-workers had to frequently step outside to call her when they had a question. To a mobile phone dork it's pretty obnoxious. To someone who doesn't even realize that they're using a different text message protocol, it is actually a pretty big inconvenience.