I believe it is from a "company" selling generic viagra and other "medications" without the requirement of a doctor's prescription. No idea as to their trustworthiness.
unless they call you on a landline - all you need is a call blocker app- if you have an Android there are many free ones and if you have an Iphone 4s or later you have o on your phone already- I have these guys under at least four numbers on my phone. they like to change it up
i do not answer any call from a number i do not recognize. but i do come here to try and see where the call came from.
my advice, don't answer your phone unless you know who it is
I do the same thing, I don't answer and have a number blocker but these calls still come through with one ring before they are stopped. They call me at least every other day. SO ANNOYING!