Audible Gifts (concept | by Bhandari et al, 2008)
The concept consists of a set of a speaker and a microphone controller. Users can leave voice messages. These two devices are not connected to each other and hence are not designed for couples to hold a regular conversation. Contrary, the device is designed with a daily limit of 5 minutes for the length of any given message.
Source: Bhandari, S. and Bardzell, S. 2008. Bridging gaps: affective communication in long distance relationships. In Proceedings of the 26th Annual CHI Conference Extended Abstracts on Human Factors in Computing Systems (CHI’08). ACM Press, 2763–2768.