phone calls with no one on line when picked up.

Put the numbers in your contacts list and assign them the ring tone "no ring".  It won't stop the calls but it will make them easier to ignore.

It needs to stop. My fancy a** I-Phone will not let me block numbers unless I pay AT&T $5.00 a month. What a racket for all of them.

CTI  When I saw that, I let it ring.  When my answering system came on, they hung up.

Pisses me off because I was taking a nap.

It appears that this CTI is some communication company that does VOIP. So, apparently, they're the flaming sphincters who provide the technology and the service that allow spammers to plague our existence with constant, unwanted calls.  It appears that their info is as follows:  (Global) CTI, 72 Fairbanks, STE 150, Irvine, CA 92618-1674, tel: 949-268-3400, website: gcti.com .  One site that lists businesses had the vice president's name but he doesn't seem to have a listed home phone. Big surprise. I suspect he hates receiving spam phone calls but has no problem with making a healthy profit by providing service to spammers so they can pester the rest of us.

Idiot caller from California (no company info listed on the caller ID).  They called our business.  I answered.  The line promptly disconnected.  I don't know if they were hoping for a man's voice or if they're autodialing system is just obnoxious that way.  Our company has gotten repeated SPAM calls from California with the same thing, they either hang up if you answer or call after business hours and don't leave a message.

Frequent calls but no one ever responds