Some use their regular cell  (non married, or the wives dont check the bill), A hobby phone, and some use google voice!

...look to the right slightly up and click on "search". Enter key words and change the days category to 300 or more.

Unless you are single & have no one to answer to EVER...  it's way tooo much risk.  Mine stays turned off & put away unless I am hobbying.  You need a good hiding spot, to be sure.  I erase all calls before I leave her...  at most someone finds a unexplained...  phone with no easy to recover numbers.  Much preferable to finding a back trail!

One, as has been mentioned, is to protect your hobby calls, texts, etc. from prying eyes, especially SO, if you have one.

Two, when meeting providers for the first time (even the well reviewed ones), you never really know what kind of person she is, or how things will go.  If it turns out that the session did not go well, or the provider turns out to be a flake or have other issues, she will not have your personal number, to harrass you or worse.  Once you have met and established a level of comfort, you may or may not wish to divulge your personal number, but it is in your control.

With that said, I too found carrying two phones to be quite annoying.  I am a divorced guy, and I own my own business, so I am not really worried about the prying eyes part.  While it is none of anyone's business, I really don't give a crap if someone somehow finds out.  I do have concerns about some unstable lady having my personal/business number number, and wanted to keep things separate.  I have dealt with that enough in the civvie dating world, lol.  I recently switched to Google Voice.  I set up an account using my hobby email, and the "name" associated with that.  There is no further validation, unless you subscribe to international calling or other services that are fee based and require a credit card.  You can get Google Voice app on your iPhone or Android, and calls and texts can be made through your regular phone using either number.  It is pretty easy to set up and works great.  You can easily turn off visual voicemail and other features that might make it easier to track your history, and you can erase whatever you wish.  One tip, when you set it up, be sure NOT to accept it's offer to import contacts!

And email should be separate as well..  But let's say you meet the love of your life & want your play history to go away.  Delete your hobby email.  Trash your hobby phone.  Know that you have not left tracks straight to your door.  PRICELESS!

Use Burner App

Burner App..iOS & Android..  
 
Allows you to create burner phone(number) right on your phone..text..VM  included...can pick area codes so you always have a local number..Keep the number a day..week..month or 60 days...you can renew number I think  
 
1st free then nominal fee for additional...no limit on how many numbers at a time or ever...  
 
Very very Useful

(I just posted this on LA board yesterday