How can I restrict my phone number from showing on the call recipient's caller ID making outgoing calls?

I just purchased a used iPhone 7Plus. On every other phone I've ever used there's been a way to restrict my number, making it private so that it doesn't show on the caller IDs of the people I call. But although I've searched, I simply can't see the option on my phone. Most of the things I've read said that it's easy to do by using this setting option: Settings->Phone->Show my Caller ID" - Toggle off. I can get to the "Phone" group of settings, but "Show my Caller ID" isn't there. And searching doesn't reveal it anyplace in settings that I can find. Please help! TIA.