The more I think about it, I actually feel like there are some situations where SMS is preferable to IM.

IM is an interactive conversation that I have to babysit. SMS is usually one-off texts with no reply or one reply.

I know that's mostly a cultural and situational bias, and maybe it's one that only I experience. Either of those communication methods could be treated as interactive conversations or as one-shot messages, they both work for those purposes. But there are things about the way those two communication methods are handled on the devices that make me tend to lean one way or the other.

For instance, Instant Messenger is a separate application that I must sign on to and leave up and connected in order to get messages. SMS is more like voice mail, and I'll get a notification of the message even when I'm not interacting with the phone. In that way, I see SMS as bridging the gap between voicemail and IM, and I think it still has its place.

Why in holy hell they charge separately for it, I still don't understand. Other than the usual reason of "greed".