Phil's daughter got a Samsung Galaxy Player for Christmas and is having trouble texting her friends on iPhones. Leo says that's because Apple's iPod Touch only uses iMessage. She can use third party apps that will cross the format divide. Check out What'sApp. There's also Kik (but not for younger kids).
There is, all of the phone companies offer this, typically for a minimal charge. They will block a variety of things, such as 'short codes' that many companies use. He should call his phone company to set that up.