Compact telephone unit with a plug-in module

A telephone unit comprising a case, a circuit including components and at least a microphone and a loudspeaker contained in said case, a switch connected to said circuit for selectively turning the circuit on and off, said case having a downwardly facing side defining a slot in the center thereof, a first multi-contact connector which is mounted on said case and placed in facing relation to said slot and comprises contacts which are electrically connected to at least some of said components in said case, said first connector providing a primary connection between said components when the unit is used alone and being cooperative with a second complementary multi-contact connector which may be plugged to said first connector and is connected to accessory circuits which are insertable in said circuit contained in the case by a plugging together of said first connector and said second connector, the microphone and the loudspeaker of said unit being disposed in said case adjacent a lower side of said case and respective grills being defined by said lower side of said case on each side of said slot in facing relation to said microphone and loudspeaker.