Well, up here, I will respond to polite PMs, but anything further than that goes through my direct email. I don't like the idea of using a forum site to conduct business and prefer things be done privately.
As for a personal number, I require confirmation via text the morning of, that our date is still on. Having contact with a gentleman in this way provides me a bit of security, but also allows for quicker communication, as someone mentioned.
Lastly, I've found that insisting on exchanging numbers and day-of communication via text eliminates a lot of time wasters. Those who are out to play games with no intention of actually showing up, are eliminated right up front by my refusal to even book a date without a cell number.
Just my two cents.