Do you use a consistent phone message?
You should remember that any point of contact leaves an impression on clients or customers so even the answering service on your phones should be taken into consideration.
Your personal mobile phone should have a standard answering message for any missed calls. Many people don't use voice mail these days, so you may as well tell people about it. Also, if you don't mind it is nice to include subtle company branding.
"Hi, you've reached Adam Cogan. If you can leave your name, number and a short message I will call you back as soon as I can. Thanks!"
Figure: Bad example
"Hi, you've reached Adam Cogan from SSW. I don't use voice mail, so please send an SMS. Thanks!"
Figure: Good example
Here's an example of how it should sound.