So the use case is as follows:

Phone is relegated to a radio device, with the NiT functioning as the user interface to:

- initiate and terminate calls, and connection is established between BT headset and handset.
- call management (call swopping, setting up multi-party calls, etc)
- send and receive SMS (NiTwill alert on new SMS received, and user can compose and send SMS from the NiT)
- NiT/Phonelink IDs incoming callers and user can accept/reject incoming calls accordingly.

In this sense, I believe you are looking for the NiT equivalent of Nokia PC Phone (http://www.nokia.com/betalabs/pcphone) for the NiT. This software hasn't worked as well for me as float's Mobile Agent (http://fma.sourceforge.net/index2.htm) did for me with my Sony Ericsson device.

The above use case would require that the user either leave the Phonelink application open (to maintain the BT connection/ping/poll between the NiT and the handset) or that upon opening Phonelink, SMS and call logs are synced automatically and quickly. The former scenario would have implications on battery life for handset and NiT since the connection is always-on. The latter would be the preferred mode of operation, IMHO.

However, i do not believe that Phonelink is able to do this today, and the UI needs some improvement (it's still too basic)