Received several calls over the past few days at various times of day. Caller ID just says "unavailable". They hang up before answering machine has a chance to answer, and they obviously leave no message.
"Rachel from cardholder services" called with a "final notice" to lower my interest rates on my credit card. Funny how "Rachel" has called me for years, even when I didn't have a credit card. This is a new number they used.