I dont think a mobile number for advertising is a good idea.
I guess in my industry its not anyway.
I have a 1300 number, which is backed onto a VOIP line, which is then diverted to my mobile phone. No one knows that beofre calling, and 1300 numbers make you look bigger than you actually are.
The 1300 number + the voip line costs me $32.95 a month. I get unlimited llocal calls, unlimited national calls, and 11 hrs to mobiles.
Since I would usually pay a MASSIVE diversion fee for the 1300 number, I got it tacked onto my voip line and use up my free mobile hours for the diversion
Its sort of complicated but once it was setup and the bugs (the stupid voip company) were ironed out I havent had a problem since. the only downside is if that your internet goes down your 1300 number goes with it.
Most people thing I am a large company, or part of a franchise, which is just want I want. Then when I say I am the owner they are quite impressed! hehe.