Jangl is a site / service for free web calls without divulging your personal phone number.
Just tried to use a site that partnered with Jangl to facilitate free but anonymous phone calls, was not impressed.
I didn't even get past the setup -- hooking up with Jangl requires you to call their number, which is a super wtf in and of itself -- it's the only phone-based authorization system I've ever seen where you have to initiate the process. It also introduces a number of errors into the process, which is why I never got past the setup.
If you own a mobile phone you'll notice that sometimes your number shows up on caller ID / etc as missing the "1" in front of it, etc, if you're making a call to a number in the same country. This completely breaks Jangl's setup process, which tries to identify the phone you're calling them with using "1-555-555-5555" while your phone shows up as "555-555-5555" if you're both in the same country. That is why most phone verification systems call or text you -- easy work around, same result.
I've only encountered one other system that worked like Jangl does, and that was my credit card company -- it is a very bad one, if you're wondering.
Also, OH MY GOD WHAT IS THAT MUSIC ON THEIR HOME PAGE?
Anyway, rant /off.