Determining Requirements for Evolving Systems

A telephone set has a transmitter-receiver including a first portion for mounting a microphone, a second portion for mounting a speaker for loudspeaking, an earphone for low speaking with an opening formed in the first portion so that the side walls of the opening connect the microphone to the second portion without acoustic coupling between the first and second portions, and a base member shaped to support the transmitter-receiver. The base member has a telephone number operating board which is accessible through the opening in the first portion when the transmitter-receiver is positioned on the base member. A mechanical switch on the base member responds to the placement of the transmitter-receiver to effect switching between the loudspeaking and lowspeaking modes of operation. Also disclosed is a microphone support member which can support the microphone without exerting any adverse effect on the characteristics thereof.