On an Android smartphone you can use call control to block calls and texts from any number. I have used it for over 6 months and it works!
Just google "Call Control" or look for it in an apps list. Free version available, but the low cost pro is much better.
My wife talked me into getting the iPhone 5c with the iOS 7 installed. Although I'm not a "smart phone" fan, I discovered a very cool thing about that phone, you can block callers just by pushing the little "i" in a circle icon,scrolling down the screen and selecting "block this caller." According to what I've read, this is a true blocking service. If they try and call again, they'll get a few rings and then a busy signal. If you try to call someone and get that sequence it's almost a sure bet you've been blocked by whoever you're trying to call.
Here's a link to the article I found this information at: http://www.wired.com/gadgetlab/2013/09/iphone-call-block-faq/
Canadian Online Pharmacy (based in India) - They have been calling me, 5-6 times a week, for almost 5 years, trying to sell me Viagra & Cialis. I was even offered oral sex by a female operator if I placed an order. I have requested help from every government agency that I could think of. The FCC & FTC (two USELESS agencies) told me that since they are based in India, there was nothing that they could do. This country is a disgrace. They can't even solve a simple problem like this.