Think twice before returning a missed call from a number you don't know.

The Better Business Bureau of Minnesota and North Dakota is warning against "one-ring phone scams."

The scheme works by robocallers letting the phone ring once, to show up as a missed call.

Victims who call the number back are then connected to a paid adult entertainment service located overseas. The calls typical cost victims $19.95 for an international call fee, plus $9 or more per minute.

The BBB said the scam calls usually come from outside the United States, but include area codes that appear as if they are regular long distance calls.

The calls are coming in from area codes 268, 809, 876, 284 and 473.