Hosiden Besson Phone Accessory, Tonecaller, Yellow

The line powered 105dBA RS Pro Loud Tonecaller is a telephone extension
sounder which has been designed for installation in large offices or factory areas which have high ambient noise levels so that a ringing telephone can easily be heard. The unit is rated to IP66 and is suitable for operation in adverse conditions.

Telephone line powered
(no mains voltage required).

Applications: Large offices, Factory or high ambient noise level areas.

Tonecallers are often used in noisy environments to increase the volume or output of a telephone ring. This enables users to hear the telephone over the background noise to ensure important phone calls are not missed.