IRS Scam - "Port-out" scam

I was doing some research about this IRS scam and found out something that is real interesting. When I scambait some of these IRS scammers, they are asking me for information like the last four digits of the social security number or sometimes the full SSN. Sometimes they ask me for my birth date. They always ask for my full name. Plus they know my phone number from the CallerID. Of course all of the information I give them is fake. But what are they doing with this information.

I discovered an article here:

This talks of the "Port-out" scam where the scammer uses the victims personal information like what was described in the first paragraph. They use it to contact the cell phone company to get control of someones cell phone. These IRS scammers may be doing this to get access to another phone number so they can continue their scam on another number. They change numbers like the change their dirty underwear. This may be how they do it.

Another question they sometimes ask me is what is the name of my bank. That may give them enough information to use the "Port-out" scam to get access to a victims SMS messages that are sent from the bank for security verification. Thus giving the IRS scammer enough information to steal money out of someone bank account! This would be before they even get the victim to go to the bank for the Google vouchers.