I currently own 2 other businesses besides starting my VA and I can tell you that my experience is that customers understand that you have other customers. If I am with a customer I am not going to tell them to wait so I can answer my phone or a email. The minute I did that I would lose that customer.

What I do is I have a voicemail that specifically says: "I am currently with a customer and will return your call as soon as possible."

Even if I am not with a customer but am having some lunch with the wife I let the voicemail answer. My customers are across town or out of town and they do not know if I am with a customer or just enjoying some family time.

But also I DO answer my phone if I am able too. In my business a missed call could be a new job that will now go to someone else.