I have done some work to locate vacant properties and want to start calling the owners. I realize that few people take calls without knowing who it is  anymore and I want to get a call back to either move forward or remove them from the list if they aren't interested. I don't want to keep spending time if they aren't interested and wont return a call if they have no interest in selling. I have a lot of time in finding the properties and don't want to fumble now, or keep spending time on dead ends.  

With this in mind, is it better to say I am interested in purchasing the house and then risk be ignored if they aren't interested, or simply say I wish to speak with them concerning a matter on the  house, for example, so they would need to call to find out what the issue is, and I can remove them from future efforts if they aren't interested?

From reading many other threads, I understand the Do Not Call list does not apply as I am trying to buy something from them, and  that topic has been covered in some depth in other threads. What is a good way to approach getting a call back or is there a better way altogether?    I have already mailed to the vacant houses and none came back with current forwarding addresses. Some may also end up with skip tracing. How might I get a call-back, whether they are interested or not?