There is a known issue with call waiting still coming through even after being shut off currently, this is being look into by our engineers. The current workaround would be to temporarily enable the do not disturb option in voice tools which would limit any incoming calls while enabled. You could also dial *70 before each call to disable it on a per-call basis.
I understand, that is where you would need to use the options I mentioned previously while we are working on correcting the call waiting from staying on. Voicemail should still turn off from voice tools, I have not heard of that not working at this time.