A number pool is a script code that you can generate in Ringba by following this tutorial.
Once created, you will then have to paste the code in the <head> section of your landing page.
Every time a user visits your website, it will display a random number from the pool. If two users are accessing the site, they will see two different numbers from their end. This is set up to lessen the likelihood of receiving spam calls.
It will capture all the information when someone visits your landing page. That way we know what phone they're using, where they are located, what page they went to, what ad they came from...pretty much all the information and it allows us to make better routing decisions who to sell it to, how much to sell it for, and stuff like that.