There's a lot of consternation about the number of services that refuse to register against a JMP number. At the core I suspect it's about information sharing โ your carrier will happily give your details to third parties, where JMP doesn't have that information to begin with.
I dealt with this differently. I stopped thinking of my mobile as my 'real' number, but instead as my public one. All personal contacts have my personal JMP number, Signal is registered against my JMP number. Cellular SMS has notifications silenced. When an SMS is important, like when logging into a bank, I know it's coming. No unexpected SMS is welcome.
This works for me because my friends don't use voice, so JMP having metered talk time doesn't matter. But mainly, I don't think of either number as 'real'. I pay for both, and each has its use.
I wrote some thoughts about this at https://blog.jmp.chat/b/2022-sms-account-verification If verification texts are important to you you can also asking JMP support about getting a "Premium+" number, which is managed by a partner who has back channels to yell at many verification providers if they reject a number.