spam calls are on the rise

Lately, I've been getting spam calls from my cell phone. I call them spam calls because, just like most junk e-mails, they're all unsolicited. What is not so right about it was that they are representing on behalf of a bank or insurance company. In fact, today, someone called me up and he said he is from a reputable bank. He even challenged me to verify his identity through a hotline number he randomly dictated. He said he called to offer automatic approval of credit card that's designed for women. Take note, it's automatic approval because I didn't apply for it but the person on the phone told me I am qualified and I get approved but only if I spare 3 minutes of my time to give him the important information that he needs. Hmmmm… Sounds fishy, right? He probably thought I would fall for it. I thought if he's from some reputable bank, he wouldn't have used a mobile number to begin with. When I declined and told the caller that I'm at work and won't be entertaining calls like that anymore, he apologized and hung up; but then after an hour or two, a new number is calling and a different voice is talking to me again for the same purpose. I'm not usually the type who is rude to people on the phone but I guess this is just one of those times that I really have to because they're just too annoyingly persistent and they're wasting my time. I wonder which part of my "NO" did they not understand? Even if they're genuine bank representatives, I tried to politely tell them I'm not interested. And who's been sharing my number to these spam callers? Now I'm really close to getting a new number. Blocking numbers wouldn't help since they can always use another disposable one.