Of course i have the right to refuse giving my personal number to clients and that's because it isn't professional. Plus it has more cons than pros, like:1- u may start getting prank calls by some clients as not all clients are mature.2- they may start calling u for anything at the company even if it's not your area of expertise coz they are too lazy to go and ask.3- they may take it as "we are friends" action and start asking you for personal favors or start calling to just talk.4- some people may call at any time which is annoying as you are not always available plus you have your personal life too.
There are more reasons of course and i have experienced this myself for a while. I was able to stop all this of course by using a smiley and nice but firm tone which worked very well but why put yourself in all this from the first place.
so i keep it personal and i have another number which i use as a work number which i open at working hours and close after work and in weekends.