Barc20- I can’t tell what your concern might be. Are you concerned about giving tenants your number, or is it that you want to manage the calls that come in better?
On the first point, there’s no need for secrecy. Tenants don’t want to call their landlord any more than you want them to.
Managing the calls is a legitimate concern, especially when you’re listing a unit. If you use your phone for other business, having separate lines can be useful. But if you’ve only got one or two units, how often is this really going to happen? Once per year maybe?
I agree with the above, wait until you’ve got more units before you add this complication.