Can I use a Busy Light with my CA12CD-S?

NOPE.

Sorry folks, the Plantronics CA12CD-S does not work with Busy Lights!

There isn’t a good place to plug them in and they use a different RJ9 connection. It won’t give you 2-way sound no matter what you try.

Not even the Plantronics brand Online Indicator will work.

(CA12CD-S/CA12CD both discontinued)