Cold callings can be annoying for the Potential customers if the call is too long for them to handle. It has been my personal experience when someone calls me randomly and I like to listen to them but at some point I find it extremely annoying and disturbing to talk with someone for so long and who is trying to get into my pocket. When I make cold calls i have no idea how long should they be. I just make the call and try to convince them about my services. But even if they want to take my services my long talks will annoy them and i am back to Ground Zero searching for next number to call.

What should be the potential length of the call so it is feasible and Bearable for the receiver ?