The cell companies will let you block a certain number of unwanted calls from specific numbers if you call them about it, but in the direction these scams are going very soon we are all going to be inundated faster than we can call the company to block - I'm not normally a fan of the passing new laws as these people seem to get around them, but maybe something could be done?
If you use your cell for business, simply ignoring them doesn't always work in your best interest.