the user to use different modes of communications (e.g. to accept a waiting call, to swap between calls, or to set up a conference) without having to understand the underlying technology.
The central element of the user interface is the so-called Communication Circle which visualizes all communication partners of a synchronous communication process. Additionally, the state of different connections (Call on hold, conference, ...) is represented inside this circle. The symbolism of a circle seems particularly well suited for this purpose given that it can be expected to be understood by people from different cultures as well as by children. The user of the system is represented by an icon/picture in the centre of the circle. This icon may be replaced upon identification of the user if more than one person uses the system. To call a partner, the user drags an icon representing this partner into the circle. Selection of communication partners is done from a structured directory by dragging either icons or phone-numbers. Access to redial lists and missed-calls lists is done in a similar way.
If the partner can be reached by different means (Mobile, video, analogue phone network, or ISDN), the user can prioritise these means, choose a default connection for each partner or explicitly choose one of these possibilities. Incoming calls are indicated by an icon / number appearing on the outline of the circle. The call can then be accepted by dragging the icon / number into the circle.
In a conference situation, all interlocutors are visible inside the circle, each one positioned on a dedicated segment of the circle. Members of the conference using the same user interface on their device see the same group in the circle on their PC with the convenor of the conference clearly marked. It is worth noting that the system works with remote parties using the same interface as well as with parties using standard telephone equipment.
In a communication situation with active partners and partners on hold, the different segments are distinguished by different background colours. It is therefore very easy to interpret the state of the communication with each partner. Clicking on the icon of a partner toggles the state of the communication with this partner. Dragging partner icons from one segment to another allows for conference set-up with multiple users.
Switching between different states (incoming call, outgoing call, call waiting, call on hold, active) is visualised through animation to make it easier for the user to understand how a communication situation changes.