Texter is a texting app that users use Twillio to send text messages to their friends.

As a user, I can send a text message to a phone number, so that I can send texts from the web.

As a user, I can save contacts to an address book, so that it's easy to text them again without re-typing their phone number.

As a user, I can send a message to more than one person at once, so that I can mass text my friends.

As a user who receives a text message, if I text back, I can get an automated response telling me that the phone number can't receive texts, so that I don't get sad when the sender doesn't reply.

Use localtunnel.me to see application in action so that Twillio can use a "tunnel" to reach your computer. 

On your Twilio numbers page, choose your phone number, then change the messaging request URL to your localtunnel address followed by an endpoint that Twilio can POST to when it receives a test, e.g. http://j384.localtunnel.me/inbound_messages.