I too received a message from "Amanda", with an e-mail address of [email protected]. Didn't recognize the area code, so I googled it. This is what caught my eye from wikipedia:

History

Although the Northern Mariana Islands (NMI) became a commonwealth in 1978 and the United States assumed sovereignty in 1986, calling between the CNMI and the rest of the United States remained an international call (011-670-XXX-XXXX). As international calling rates began to fall in the more competitive destination countries during the 1990s, it became a considerable financial burden for people calling between the U.S. Mainland and the CNMI.