What number does the person I call see?

Two situations turn this from a detail into the whole problem. A bank or airline that identifies customers by the number they are calling from will treat you as unrecognised and take you through its full identity questions, so have your account details ready before you dial rather than hunting for them in a queue.

The second is a callback. If the person you reach says they will ring you back, they will ring the number they saw, which is not your phone. For anything where a callback is likely, renting a number you keep is the answer, because then the number they see is a number that reaches you.

Renting a number gives you one that is yours for as long as you pay for it. Calls to it ring your browser, or forward to your own phone when the browser is closed, and it is the number shown when you dial out.

Verifying a number you already own is the other route. You prove control of a phone you have, by answering a call to it and entering a code, and afterwards calls can present that number instead. It costs nothing to run because the number is already yours.