Mood can also play an important factor in your recording. Record the greeting in a quiet place, remember to smile, and focus on leaving a positive message that’s sure to please your customers. (Tendant provides an example script you can leverage for your voicemail greeting.) Cut through the noise by speaking clearly. From honking horns to spotty cell service, callers often have their own background noise to contend with. The last thing you want is a missed message due to a lack of clarity, so make sure your outgoing greeting is clear, concise, and recorded at a reasonable pace.
Lines and extensions: With an analog phone system you might, for example, pay your telco for two or four lines to allow your business to have that many simultaneous phone calls. For that to work, you'd need a two- or four-line analog business phone system, which are some of the most common analog systems on the market.

State your name clearly so the caller knows they have the right number. 3 of the messages I heard last month were missing his/her name.
The best free virtual number provider at the moment is Google Voice. It trumps the competition since it gives US users a permanently free virtual phone number. You need a Google account to sign up for the service. Once you register, you will type in the city you want your number to look like it's coming from and select one of the available numbers.