Symbol 5576 from IEC 60417 - Title/Meaning: Bell cancel Function/description: To identify the control whereby a bell may be switched off or to indicate the operating status of the bell.
Additional information: 
As far as there is no danger of confusion, this symbol may also be used for ""acoustic signal, switched off"".
The graphical symbol may be used for temporary bell cancel by replacing the negation cross with a cross of broken lines
Published in: IEC 60417 database on 2002-11-03 by C00020.
Own work using: iso.org/obp/graphics/grs/7e3dc5bd-7788-4744-aceb-ded8d763db48 200.png
Vectorization:  Mrmw