arduino and nokia 8310 fbus interfacing


I would like to interface my arduino witj a Nokia 8310 for making start a call basing on some conditions.
Now the 8310 has fbus connection (ground, tx and rx) that works at 3,3V.

Can You pleas help me in fixing the following problems:

  1. I need a simple scheme to let 3,3V tx/rx work with a 5v tx/rx
  2. I want to use the Arduino Uart, is it inverted?
  3. I want to use At commands, is there any code/library already avaible?