My 3 yr old daughter recently started asking about her estranged father. How do I answer her w/o hurting her?

My daughter is 3 1/2.A few weeks ago she started asking about her father. (Her father and I were together 4 yrs. He split when I told him I was pregnant.) I took him to court a year ago for child support and the issue of visitation was mentioned. When I informed him that our daughter has asthma and she can't be in a house with smoke or pets, his response was "Its not worth it, I didn't want to see her anyway, I was just trying to make you mad." He then declined all visitation rights. Now, my daughter keeps asking about him. (With her best intrest at heart, I have kept her unaware of his feelings towards her) She asked for his phone number. At that time, I didn't have his number, so I answered her with all honesty, "I don't know." Since then he has called me to set up payment arrangements, so I now have his number. Do I tell her I still don't know his number? Do I let her call him? She asks a different question about him almost everyday (his name, age, what he looks like)Please help?