nothing that pertains to BlackBerry handhelds, from my experience. there's PIN messaging, which is a handheld-to-handheld-directly-over-the-RIM-network communication utility - now with a GUI interface deemed BlackBerry Messenger. perhaps in the older days, SIM messaging would refer to SMS messages, since they were stored on the SIM card...? or perhaps its simulator/simulated messaging, a la sim city or the sims...?