Block unwanted calls with ATT wireless home phone

I have had my phone number transferred to my new address.  The phone number and the phone itself was a landline for years and years.  Now it is running off of the ATT wireless box ..the one with the antenna.  I asked ATT how to make the call blocking service work. I am getting a load of calls that are telemarketers and foreign people wanting to fix my computer or telling me I have won a sports car etc....

ATT told me that since I am using my handheld phone instead of a cell phone that there is no way to block calls using ATT wireless service.  I prefer my handheld phone over a cell phone because it gives such a clear connection compared to my cell phone.  I am paying for call blocking as part of my features package but they tell me I cannot use it???? 

Surely someone on her knows how to block calls through the wireless network that rings into my ATT handheld phone?  

Please help find a way. These telemarketers are driving my nuts.  And yes I am registered with the government DO NOT CALL LIST and have been for years.