Lol, it does seem to be the teenage girl satcom method of choice =)
That said, it's worth noting that the messaging, while being two-way, does require initiation on the inReach end of the game first. The device doesn't have an email address that can receive a message, nor does it have its own phone number that can be texted. I suspect this is partly to keep traffic limited to persons you want to have using up your battery and precious quota, and partly as a cost saving measure that keeps DeLorme from having to acquire and provision pricey phone lines.
There are basically three ways to have messages come to you in the woods...
Option 1 (no particular order here): If you enable it in your account settings, the generic shared map page can have a button that anyone can click on, and fill out their message to you. (You can also password-protect that page if you want to.) They do have to provide a reply phone number which pretty much has to be a cell phone since it will function using normal text messaging thereafter.
Option 2: You can send someone a message from the device (or via paired smartphone which is much quicker/easier) via text message. That is to say that the recipient will get it on their mobile phone. They can then reply to that message as much as they/you want. The number they are replying to is NOT assigned to your device though. There's an explanation of the process on the DeLorme forum, but basically when you initiate contact, the servers create a record of the recipients phone number, your device's unique network ID, and the phone number that the server picks to send the message to your recipient. When they reply back, it uses that info and the inbound caller ID information to route it back to you wherever you may be.
It sounds overly complicated, but works really well in practice and is the quickest way to establish a communications channel that can be used for back and forth chatter.
Option 3: You send someone a message from the device via Email. They get an email and inside it is a link to a DeLorme page. It'll show your location on a map and provide a text box they can type in to reply to you. If you reply back, they get another email and the cycle starts over.
This method might be easier for non tech savvy recipients, or people who can't/won't use SMS. (My own mother has a cell phone, but the day she figures out how to type out text messages on it will likely arrive sometime after cold fusion and world peace. And perhaps unicorns flying out of a monkey's ***. =)