Insurance company. Uses other numbers too. Look for the 831-221 and if you don't recognize the number, don't answer. If it's important, they will leave a msg.
Online pharmacy scam. Blocked the number but does no good, they will have 10 new numbers tomorrow. I've had the same number for 15 years and use it for business, actually considering changing because of these asshats.
Steve, it won't do any good to change your number. They don't look the numbers up in a phone book, or call information to get your number. They use a robo-dialer that dials every number combination in sequence until they get a "live" one. The Do Not Call list doesn't stop them, either, because they are criminals looking for an easy mark. Legitimate callers use the DNC list, but criminals don't. A call blocker is the best thing to do, but even that wont stop all unwanted calls.