I don't know how hard it would be to implement, but it would be a game-changer if you could send a message to a (currently unavailable) user on Arrowchat (still shows up on the list) and have that message sent to their mobile phone via SMS.
Sort of like how AOL instant messenger does. Or even Facebook (although I think it sends the message via their app). After that, the mobile user could send a msg back to the online user (back and forth)
I believe you would have to define a mobile number field for new users..
Could this be integrated?