The International Routing System phone calls are a scam. I found another blog post about them that was dated 2010. I must admit, this is the first I have heard of it. Here is a quick rundown:
Someone calls your phone and tells you that your IP address is generating lots of traffic and it is interrupting the IP tables or something to that nature. If you let them keep talking they will want more info on your computer system and have you install spyware, trojans or what have you.
There is no such thing as an International Routing System. They are calling through the internet so there is no way to block them. Google Voice is suppose to have a new a feature that forces people with blocked numbers to record their name. Not sure if that would do any good.
The individuals calling my friend’s phone number are now calling multiple times a day and sound Latino.
The only advice I have is to hang up on them as soon as they call. Eventually they should get bored and move on.