Symbol 5999 from IEC 60417 - Title/Meaning: Telephone, ringing Function/description: To identify the control for the ringing level of a telephone, or to indicate the status of a telephone being called.
Additional information: 
Published in: 3C/1531/CDV, 3C/1549/RVC
Own work using: iso.org/obp/graphics/grs/dff09145-23d5-4af2-b079-92b8ae341fb7 200.png
Vectorization:  Mrmw