rSAP (or SAP) is used for mainly Nokia carkits. Many European manufacturers as Volkswagen, Seat, Skoda, Mercedes have it on their cars. The carkit connects to the phone, copies the SIM data, then puts the phones own transmitter into offline mode and uses the data from the sim to bring online it's own transmitter. For increased reception, lower battery usage on the phone and great voice quality. Great service.
There have been number of entries on bugzilla (5204, 7182) and talks (34027, 31962, 35756) about this. This just has to be part of Nokia N900 bluetooth profiles.
It's really sad that N900 (Maemo) doesn't support this bluetooth profile out-of-the-box.
Thread to discuss: http://talk.maemo.org/showthread.php?t=34027
