Blizzard has recently updated its article about its 2FA system. It explains that Call of Duty: Modern Warfare 2 and Overwatch 2 now require a phone number to make an account to play the game. While most gamers have access to a mobile phone, there are a few restrictions on what kind of phone someone can use.
According to the article, users with a pay-as-you-go contract on their mobile phone may not be able to sign-up to Battle.net or play the listed games. It states these phones “may not work with the phone notification service” and that it doesn’t work with VoIP or VoIP numbers transferred to a local provider. The page also confirms that messaging apps are not supported on iOS or Android phones.
When this system was first added to Overwatch 2, players on prepaid mobile phones were locked out of their accounts. Blizzard did apologize for this and removed the phone number requirement for players who had been signed up to Battle.net for more than a year.