Another "technology" that isn't supposed to exist
SMS is so absurd, it is technically an ISDN phone call with dialing process and everything, just to deliver those ridiculous 160 characters.
But since those bellheads didn't want a packet based telephony system, sending message packets had to be embedded into phone calls.
Alright, that's history. Today we have GPRS, UMTS and dunno what. Yet everyone is still fumbling around with those SMSs, and our mobile phones typically provide for no decent messaging technology. Even if they did, there is no standard.
It has been obvious for ages, that a real packet based messaging system belongs into mobile phones.. I mean, it's even written in the 1997 article on PSYC that appeared in konr@d, the technology spin-off of stern magazine, Europe's largest weekly at that time.
Okay so in the meantime clients for several inappropriate protocols have been implemented for mobile phones. Not very efficient, but it's a start. Still, you would want a seriously compact protocol to run through your GPRS, especially when you're not paying it flat.
Compact PSYC should certainly be a better choice than anything currently in use, and it is also much better extensible.
But hey, who am I talking to. You know these things anyway.
At this point in time the real question isn't even about optimization. It is about getting started in the first place. How would we discover, that our friend with mobile phone number XXX-XXXXXXXX also has this or that chat protocol running on his phone? Looks like we need a directory service for that. Maybe an even distributed one.
See also: Mobile access.