From the picture in Section 2 of "Learning more about Ooma Quality of Service (QoS)" (https://ooma.custhelp.com/app/answers/detail/a_id/112), if I set my QoS upstream to 800kbps and my downstream to 8000kbps, then the max I would ever be able to download at is 8000kpbs and the rest would be unused bandwidth.
But in my real test, I set QoS downsteam to about half my max download speeds, but I'm still downloading at max speeds. Shouldn't Ooma QoS cap my downloads to half the speed?
In other words instead of any and all traffic between your site and the Internet going through equally well, the QoS settings give priority to packets to/from the Ooma. If you're not on a phone call, then everything proceeds as before. Tell us about your download speeds while you're on the phone.
In other words, the bandwidth is not permanently set aside for VOIP, but allocated only when you're actually conducting VOIP.