The modified N900 attaches a resistor that responds to a squeeze at four different pressure levels, and doles that out during a traditional or Skype-based call as a vibration on the other end.

ENGADGET: ForcePhone from Nokia Research, HIIT sends positive vibes with a squeeze

As it is made entirely out of circuit board, users can solder components directly to it -- such as a light dependent resistor or a microphone to make it respond to sound.

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