Sorry bro, why? why is the question?
There is a whole list of reasons that the topics on this subject will all have. But I will list the two most obvious why
everyone should have a punting phone.
1. Prostitutes will phone you at potentially any time they wish and for any reason. And they are not discreet when they do.
Every punt you ever do, the girls will store your number in their contacts list for-ever more (I am talking keep it for years later from one punt!). This means you are at the risk of the girl accidentally phoning you when she wanted the other Mark in her lists but phoned you by mistake. Or phoning you to make offers if her bookings are low. Or phoning you to have a rant if you ever say something she dislikes on the forums.
2. Prostitutes will post up your number willy nilly on public forums with "he is a punter" and this is what he has done. It seems to be the trend going about at the moment.
Now how would you like to be going for a job with this number on the top of your CV uploaded electronically and a job serching streaming app automatically searches the web for it and finds a load of comments about you being a punter who was timewasting a prostitute (or worse).
Or how would you like a girl you met at a bar and you gave your number to, for her to google it.
Or an old school-friend on facebook you gave it to, and they google it.
And before you go, "its ok, I wont ever do anything bad to a working girl to make her ever do this". I remember being told a couple of years ago by the owner of the agency I used, Diamonds. That this girl I had seen and really liked (Cindy)
https://www.ukpunting.com/index.php?topic=25180.0She was sacked from them as she claimed a punter had stolen the money from her. It apparently caused a whole load of aggro. And it turned out at the end. She just didn't want to pay her commission to the agency so came up with this story about the punter expecting the agency to just go "ah you were mugged, ah right, thats ok, you don't have to pay us then"