Stop not allowing VOIP numbers. SMS verification can easily be performed with VOIP. Twitch is attempting to farm unneeded information by tying a form of account verification to having and providing a phone number that corresponds with a large telecommunications company. Not only is this incredibly invasive and not at all conscientious, it also serves as a financial barrier to those who are unable, or unwilling to get a normal phone number. Not everyone needs to pay the unneeded money to ATT or a similar corporation. VOIP numbers work just fine. Adding insult to injury, is that you can even physically stream. They will still not verify you with a VOIP number, on the justification that they can't use it to "verify" you, which is absolutely insane when you are a physcial person that uses the streaming function, has followers, and a two step email verification already established. Let's also add, that it prevents a layer of security I could additionally have through added 2 step number verification, because Twitch wants to LIE about it's inability to be used for verification. That's not the issue. They want to know where your zipcode is, and that you pay a communication's company a monthly service fee.
Organizations I do business with on a regular basis, using a VOIP:

My doctor/hospital, and other medical service providers.

My bank.

My various places of employment.

The federal government, most particularly the IRS.

Organization that don't like my VOIP number, and try to act like a normal one is needed in today's world:

Twitch

Twitter.

It's very easy to see who is out of line and farming customer data