Speakerphone accessory for a portable telephone

A speakerphone accessory for use with a portable telephone, the portable telephone including a microphone, echo cancellation software, a user interface, and a power supply disposed inside a telephone housing and coupled to an input/output port, the speakerphone accessory comprising:

• an accessory housing having a front wall and a rear wall joined by a side wall to form an enclosure, a central wall projecting from the rear wall into the enclosure having a first end covered by the rear wall and an open second end, and a first acoustic port and a second acoustic port extending through the rear wall;
• a transducer attached and covering the second end of the central wall, thereby dividing the enclosure into a first acoustic chamber defined by the rear wall, the central wall, and the transducer, and a second acoustic chamber defined by the transducer, the central wall, the rear wall, the side wall, and the front wall, the first acoustic chamber fluidly coupled to the first acoustic port and the second acoustic chamber fluidly coupled to the second acoustic port;
• a control board coupled to the transducer;
• and
• a connection port coupled to the control board and positioned for connection to the input/output port when the accessory housing is attached to the telephone housing.