TLDR: Trust your senses and throw this fish back in the sea
Burner phone is a common way to say it where I’m from. Burners are the ditch phones. But I digress…
In the US we can look up a number and at least find out who the carrier is. If it is one that is common for cheap burner type phones then it’s a clue.
It’s also a clue if he does not have a voicemail greeting, or does not use his name in it.
Another thing to look out for is apps that allow a phone to have two numbers. Mine does because I use the numbers for signing up for stuff as I’m sick of spam calls.
It doesn’t look good to me. Hopefully you love yourself enough to trust yourself.