Do I have to give OpenAI my phone number?

I'm just a bit concerned about privacy and security. Is it absolutely necessary to provide my phone number to OpenAI? I understand that they may need some form of contact information in case there's an issue with my account, but is there an alternative way to verify my identity or reach out to them if needed? I'd like to use their services but I'm hesitant to share my personal information without fully understanding why it's required.