Most small business carry cell phones and conduct business that way.we just don't happen to have the cell numbers. Most are not even in the office 90% of the time. General voice mail boxes are rarely checked as most messages have nothing to do with business. Businesses are more mobile now with cell phones, text and emails. Not 1970 anymore guys.
Not saying it is correct but have seen it a lot. Trust me, cells never gett out of range and I would bet customers know how to contact them.