Hello.
I have asked Nokia Care about this.
And:
N900 Does not have support for PBAP (Phone Book Access Profile). and there for N900 can not show whos calling on the BH-903.
Also, N900 only supports version 1 of Audio/Video Remote Control Profile (AVRCP).

The differens between the AVRCP profiles:

* 1.0—Basic remote control commands (play/pause/stop, etc)
* 1.3—all of 1.0 plus metadata and media-player state support
o The status of the music source (playing, stopped, etc)
o Metadata information on the track itself (artist, track name, etc).
* 1.4—all of 1.0, 1.3, plus media browsing capabilities for multiple media players
o Browsing and manipulation of multiple players
o Browsing of media metadata per media player, including a "Now Playing" list
o Basic search capabilities