When Blizzard shut down Overwatch 1 they required a real phone number to transfer your items and log into Overwatch 2. Tried a Google Voice number, nope, they require your real phone number. There is never going to be a situation where I want Blizzard contacting me on my phone.
…and that is why when they finally turned off the Overwatch 1 servers, I stopped playing Overwatch at all.