Ed, it didn't mention RJ9! Someplace I read a reference that claimed that 4P4C is an RJ9. All I ever called it was handset cord plug/jack.
OOPS, after double checking, it does mention it as 'un-official' designation. I guess I'm semi-vindicated, based on the description.
I guess it's just another case of someone trying to be technical in a field where he should be plowing instead of thinking! smile John C.

When I was young, I was Liberal. As I aged and wised up, I became Conservative. Now that I'm old, I have settled on Curmudgeon.