Automated dialing/calling system. "sounds" like a real person but in fact only listens for "yes/no" style answers and tries to talk back like its a real person. Pretty easy to tell the difference by asking questions its not prepared to answer.  Also, when they ask if its "ok" for one of their partners to call you, keep answering "no" to all those questions. Eventually it will hang up and you've now "opted out" of their system.  Painful, but did that before blocking the number

Calls multiple times a day. Annoying

Illegal scam call.

Rings several times, then hangs up...frigging annoying.

Call several times but no voice message.