Skype is a separate service that you cannot host.
Teamspeak is trash for the most part, the codecs are terrible quality.
Ventrilo is pretty much the only way to go for voice hosting.
Its not quite as simple as paying to be put on the list of providers. You cannot simply just purchase Ventrilo server licenses directly from ventrilo, you are pretty much forced to Resell slots until you have enough customers to qualify for your own licenses.
In order for an applicant to be considered you must meet the following minimum requirements.
1) You must have a legitimate business license in your state, country or jurisdiction. Please be prepared to provide proof when requested.
2) You agree to a 1000 slot minimum. Slot counts greater then 1000 are billed at the per slot rate for the total number of slots hosted. Slot counts below 1000 are billed at the per slot rate with the required minimum of 1000 slots.
3) Licensee's slot counts are expected to grow on a regular basis.
We do not license individuals or businesses who wish only to run one or two standalone servers. In these cases you will need to rent a server from one of our official licensees on the hosting page.
As for QOS, you shouldn't really be having to worry about this, you don't really want anything being choked off by a QOS, neither game servers or voice servers.