Symbol 6000 from IEC 60417 - Title/Meaning: On-hook dialling Function/description: To identify the control for making a telephone call without picking up the handset.
Additional information: 
Published in: 3C/1532/CDV, 3C/1550/RVC
Own work using: iso.org/obp/graphics/grs/2d171e97-1635-4ca9-8189-8b1d6b0283fb 200.png
Vectorization:  Mrmw