Viewers are invited to dial one number for "yes" and another for "no". These surveys cannot possibly give a reliable indication of the views of the population in general, since there is nothing to stop individuals dialling the number of their preferred answer as many times as they like, and interest groups can do the same thing. To get reliable information about the views of the general public, there is no substitute for careful, well-designed sample surveys, with random selection of the respondents.
Next time you see a TV phone-in poll yell "Boo!" at the television, and throw something (soft!) at it.