This number is the commercial billing number for calls from Military overseas. This is a second dial tone line. They should be dialing 800 toll free directly instead on DSN. This number cant be dialed from a commercial phone. These are calls from Military persons Overseas using 800 toll free type numbers or calling cards.

So, what kind of scam is this?  Do they bill you for overseas calls or what?  I don't know anyone stationed abroad at this time.

This is a scam. You just gave permission to get billed for long distance to a new company. Watch your next phone bill and a new charge will be on it from "level one" they are a billing company for the scamming party.