"So, if you have never been with me, get horny before 10pm, OK?"
Classic line...owe you one for that.
Sassy for real.
I think there are a couple of sides to this. Yes, I think there are probably many men who just pick up the phone when the are in the mood, and think "This is what they are there for, so ooo rah!".
However, there are some providers who don't have a problem with that, so there is not a universal code. In addition, I myself was stood up on my first attempt to see a provider more than a year ago, and know that when you are stood up at 11pm, it is strongly tempting to just pick up the phone and try someone else. I didn't, but when I called another lady at noon the next day, I went direct to a voice mail. I was pretty hot to see someone, so I called her back again at about 5pm, got voice mail again, and tried one last time around 9:30. I figured, hey, VM, what does it matter, right? Well, this time, she was there, she picked up the phone, we talked for an hour, and she decided to come over at midnight, and it was great for both of us. I would never have requested it, but I sure was happy she did.
I think the best you can do is list your hours to call on your website, have a separate phone for "business", and not have it ring after a certain hour. There will always unfortunately be people who abuse it, but that should cut down as much as anything else would.
Sweet dreams.