I have summarized various hints for making Address Book as compatible as possible with the Sony Ericsson P900 (over Bluetooth) on this page
Answering, dialling and hanging up calls are all possible, but please note that SMS send/receive is not due to the P900 having no support for SMS "AT" commands over Bluetooth.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20040430122404588