There is a fairly common IRS or "tax scam" being practiced by scammers in both Canada and the USA.
USA tax payers should read this:
http://www.irs.gov/uac/Tax-Scams-Consumer-Alerts
Note particularly the links at that site, warning of the scam!
Success! Magic jack emailed me to to follow up on the abuse report I filed about this number. It has been shut down. I know there are still other numbers being used, but at leasr we know Magic Jack will do something if you report it to them. I have filed a report for 241-4918 also.