If I may add my 2 cents here, my bf has never met with his father and had always wanted to until recently. Now he doesnt care to know him. His father abandoned him before he was ever born and will not ever know him for the great man and father he has become today. I dont blame him none. But on the flip side, I would tell your son and let him decide whether he wants to contact his dad. He is a man now to make his own decisions. I dont think I'd keep it from him incase he is secretely alway wondering about his biological father and doesnt bring it up for fear of hurting you and cause you pain. It may be he will completely disregard his dad and then again maybe he wonders. When you are ready Id present him with the fact that his dad called and only give him a number to call him so the decision is his. This way he can make his decision with out someone taking it from him if he is so inclined. Your a good mom for trying to figure out what is best intrest of your son even now. Hugs to you.