WARNING--BEWARE!! These callers are B I G credit card criminals, known as the card service scammers! Under NO circumstances, give these lowlifes your credit card number, or you will regret it forever!
Try getting a copy of PhoneTray. I've been using it for years and it's very effective in intercepting unwanted phone calls. They even keep an online database of scammer's numbers. All you need is a PC and a USB Data/FAX modem connected to your land line. Check it out!
Look through the information pages at the beginning of the phone book; there are usually instructions for blocking unwanted calls. It may take a week or more for this to take effect, but I have many fewer junk calls than in the past. Today was my first call from "Service Dep." so I hope the blocking works this time.
The card service scammers WILL 'service' our credit cards, BUT, when they finish 'servicing' them, they will have NO available credit remaining! People that are fooled into having their cards 'serviced' will be charged a MINIMUM of $795.00, and many times the ENTIRE amount remaining on the card. The card service scammers are a disgusting group of degenerates, who prey mainly on the low income, and the elderly, but will cheat anyone that they can!
Actually, a better 'option' is to wait for their 'rep' to talk and rip into them with 'sailor' talk and threats. It's a BS credit card robo scam that threatens you about final warning and a respectful will soon talk to you...push '1'.