how to activate SIM without being able to call cosumer service

Hi, lost my phone so I ordered a new SIM card and am trying to set up on an old phone I have. Everything on the website about activating my SIM card sends me to the "contact us" page. But I don't have the ability to call because my SIM card isn’t active!!! How do I activate my SIM card without being able to call costumer service? It is not a new phone, so when I power off, insert sim, and power on, it doesn't give me a set up page.