I have to disagree with Tom and Jacqui on this.
To me, a mobile number would indicate that I'm definitely going to get a human being on the line, and that it is likely that my enquiry will be dealt with immediately.
I would simply add something like "Contact Calvin on Mobile: 1234567".
I say this because I made the same mistake with my yellow pages advertisment in Sydney for my signs biz. One year I omitted my mobile number and the enquiries dropped noticeably. The personal touch is very important.
This "personal touch" is why I will sign up with matrixx for web space if he offers a direct telephone line. If he doesn't, then I'll shop around for someone who does.
And anyway, I doubt very much that in the worst case, people will not contact you because your mobile is there!
Dave