How could I message a dumb phone and an iPad at the same time I have an iPhone and my friend has a regular old dumb phone and an iPad.  At school, she has no cell service, but she does have wifi on her iPad.  Everywhere else she has her phone, but doesn't carry her iPad, so I have no idea which device to message.  

Is there an app or service I could use that would message both at once and keep the conversation intact on all of our devices?
You can send a text message to multiple recipients at once with the built-in Messages app. Just send a message to both her cellphone's number and her iPad's email address.