We developed AffectPhone, a system that detects a user's emotional state using the GSR, and conveys this state via changes in the temperature (wamrth or coolness) of the back panel of the other handset. Since GSR is a good measure of a user's level of arousal, we detect the GSR using electrodes attached to the sides of the handset. When the user's level of arousal increases or decreases, a Peltier module in the back panel of the other device generates warmth or coolness. This system does not require special sensors to be attached to the user's body, and therefore, it does not interrupt the user's daily use of the mobile phone. Moreover, this system is designed to convey non-verbal information in an ambient manner, and therefore, it would be more efficient than displays or speakers. This system is expected to help enhance existing telecommunication.