Your carrier is ripping you off to save money.
OK: That's not fair ... one of the Telcos that supplies your carrier is ripping your carrier off. Unfortunately, you're paying the bill (and your carrier still gets paid), so perhaps the first description was closer to truth. LOL
Where was I? Oh: What is happening is "false answer". They have detected that you are generating a lot of fake calls (ie: you're dialing numbers that don't exist, and numbers where the people you're calling are not going to answer for whatever reason). To punish you/rip you off for this, they fake an answer immediately and bill you for the rest of the fake ring time. Now you're paying for time that used to waste their equipment's time.
Complain, tell your carrier to remove the false answers. Be sure to have a log of at least 10 calls with specific phone numbers and call times down to the second with time zone included. Your carrier will complain to his aggregator, the aggregator will kill the telco committing the offense, and they will all refuse to refund any of the ripoff fees. If you have a negative balance, I'd suggest getting a live account with another carrier immediately (before beginning this process).
Have I mentioned that it's always a good idea to have AT LEAST three carriers?
Happy Hunting!