Cons:

You absolutely cannot get 2FA authenticator codes from 90% of services. Many services that require a phone number even without 2FA just for “verify you’re a human” or because they want your data or to verify region use shortcode services that also will not work with ANY VOIP provider.

You will not receive their codes. These companies vary from banking institutions to gaming companies to online shopping marketplaces and stores to a Google account (used to be you could get an automated phone call to verify an account, not anymore, must be able to receive SMS from shortcodes that are disabled for VOIP numbers to register and to recover an account) just about anyone you could end up doing business with.

A shockingly large amount of companies demand phone numbers and send verification texts before allowing you to do business with them, to create an account, to recover an account, to delete an account, to place an order, etc.

They really shouldn’t, it’s a bad security practice but companies love it because with a phone number they can lower support costs by just allowing people to do a self-service where they get an automated text and can unlock their locked account. They also love harvesting that data and preventing anonymization with VOIP numbers and the reduction of fraud and increase of reliable KYC that comes with requiring them.

And they all take it as a given that EVERYONE or at least 99% have a cell plan with a non-VOIP number that works with these and the 1% who don’t they don’t care about in the developed world and are an acceptable loss.