Obtain iPhone unlock code for unused old iPhone

I have an iPhone 5S, for which I have tried to obtain an unlock code so I can give the phone to a non ATT subscriber.  I have run into numerous roadbocks.  Initiallly I was informed that my number is not with ATT which is untrue,  I have been with ATT for years now with that number.  I went to a local ATT Store and lady there helped me and gave me a confirmation number and said I would receive an e mail within 2-3 days.  I never received such e mail.  Now I have been informed the unlock request has been cancelled and I must resubmit it.  Now when I go to the ATT unlock page, type in the IMEI number and click the button, the page will not open.  Can you please assist me with this matter.  I merely want to unlock this old iPhone SE so can give it to a family member who does not subscribe to ATT.