Telephone Hybrid

https://www.epanorama.net/circuits/teleinterface.html

Traditional transformer hybrid circuit

updated model

https://tinyurl.com/22o35npc

https://tinyurl.com/yzw6rao7

https://tinyurl.com/2a7e72mw

https://en.wikipedia.org/wiki/Hybrid_coil

https://en.wikipedia.org/wiki/Telephone_hybrid