All inspectors should have a dedicated phone number--and even a dedicated phone--that's used only for new business. In fact, this dedicated phone should be red in color (which you can easily make by using a basic colored cell phone cover). An actual red phone is your instant reminder that there is no phone call that you'll answer all day that's more important than a call for new business. This red phone should have the phone number you would list in any and all advertising that's designed to acquire new clients, such as emails and newsletters to new potential customers, print ads, truck signage, yard signs, billboards and direct mail.
You can use a different “main” number in your contracts, for suppliers, on your inspection reports, and for general business use. That way, you or your staff can man the red phone and leave the other phone number to be used primarily for everyday, routine business. The red phone should always be manned because it means new business, and you should never let new business get away under any circumstances. Set up your free "Call Me Now" button on your website to ring at your red phone.
You could have two numbers go to one phone, but then you wouldn't be able to give just your red phone to someone to answer.
If you’re a one-person operation, be sure to ask your clients whether they’d mind if you took calls during your meeting with them; most of them won’t object if you ask in advance. Let your everyday phone calls go to voicemail if you’re busy, but always answer your red phone. Prospective clients won’t be interested in leaving you a voicemail (they are under time constraints); they’ll just move on to the next inspector. If you carry both phones with you out in the field, make sure your “everyday” phone is turned off during meetings. Make both phones’ ringtones different so that you know which phone is ringing so that you can pick up any "red phone" calls. If you're on an inspection with a client, ask them for permission to answer your phone during the inspection. Your client's confidence in you will increase if s/he sees you are in demand from other consumers trying to hire you.