Abstract: A basic call in a telecommunications network provides a transmission path between two users. Additional functionality is provided by a set of services, wherein, if a number of services is invoked during the same call, it is important that the services do not interact adversely with one another. For detecting service interactions, a service abstract is produced based on a Basic Call State Model and a data processing sequence performed by basic call state processing and by the services in respect of a global data item.

Abstract: A lock comprising a stationary sleeve, a hollow cylindrical member, a tubular member and a means for rotating the hollow cylindrical member. The stationary sleeve defines a spirally extending slot that extends its entire length. The spirally extending slot is formed between a first edge and a second edge of the stationary sleeve. The hollow cylindrical member defines an axially extending slot that extends its entire length. The hollow cylindrical member is movably positioned within the stationary sleeve. The tubular member has a projecting tab fixed thereto and is slidably disposed within the hollow cylindrical member wherein the projecting tab is slidingly engaged simultaneously within the spirally and axially extending slots. The rotating means causes the hollow cylindrical member to rotate in a first direction or in a second direction. When the hollow cylindrical member is rotated in a first direction, the projecting tab physically contacts the first edge of the stationary sleeve.