Call Waiting doesn't seem to work

[Lord Vader]

This has been going on for quite some time, but only now have I bothered to let it annoy me. Whenever I am on a call and get another call, I can hear the call waiting beep and see on my handset who is calling. I can even flash over to that other line and the caller, but the problem arises when I try to flash back to my original call. Every time I do so, I get the dial tone; I'm disconnected from my original call. This happens on my own phone handsets as well as the Ooma Telo handset. No matter what I do, I cannot switch between calls without the first one getting disconnected.

[Tom]

please post date/time/zone when this last happened or when it happens again

[Lord Vader]

I don't remember each time it happened, with the exception of the last time, that being yesterday at 7:17 p.m. CST.