I am very cautious with sharing my personal mobile phone number. Especially online. I only share it with live people whom I find to be pleasant and trustworthy. But what about all those online accounts that require a phone number?
If I had a Gmail account, I would set up a free voice-over-IP (VOIP) phone number with Google Voice, available with my Google account. With the Google Voice app on my mobile phone, I could send/receive phone calls and text messages and not have to share my personal mobile phone number.
But I don’t have a Gmail account…
For the past four or five years, I have used a masked mobile phone number with Ironvest. For $40/year, I have a phone number that automatically forwards text message notifications to my personal phone number. This way, when an online food delivery website gets hacked, The Adversary only gets my masked/alias phone number, not my personal one. And if I ever get bombarded with text messages from a number, I can sign into my Ironvest account and turn off sending messages from that annoying number.
Bonus use: Single folks who meet someone intriguing can share their masked/alias number to receive communications. Should things take a turn for the awkward, that not-special-anymore someone only has the masked/alias number, and you can block their number before it ever reaches your personal phone number.