Had this happen a few times.......one occasion was the 'secretary' for the girl arranging the booking, which was just indeed that, as no bait and switch and girl was great, and other times have been (English) girls who trust me using the private phones to contact me back, and I now use those phone more often than not...
This method is used by numerous (English) girls, giving you their 2nd number when happy once they have spoken to you or read your email, or have seen you before. They claim it to be from their private phone, but sometimes it is their 2nd punting phone. Either way, it is their way of saying you have my private line, even on days when they don't pay £5 per day to display their number. Over time, I know of quite a few girls who then don't bother displaying their AW number that often, relying on repeat customers from their 2nd phone, and only going back to display their AW number when business is low with their regulars.
From experience, PG Scammers will simply not answer when called, then tend to text you back to say can't speak but please text back. If you are polite and say you will not book unless you speak to them first, the genuine ones will text back to say call them.