Does Asterisk support user sign-up themselves?

Hi, I am new to Asterisk.

Can somebody tell me if Asterisk support user sign-up? I mean any user can sign-up themselves via the web and get a number, and then they can setup their own standard SIP hardware (like Cisco ATA) to make a call.

Basically this is like vonage website.

if Asterisk does not support user sign-up, is there any software (free or paid) to do this? Thanks.