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.
Rollover Hunting is a feature that is managed by the Account Manager or Phone Manager. It allows incoming calls to your primary phone line to roll over to the next available line and, if al l lines are busy or not answered, the call can roll over to voicemail. It will hunt through all lines in the group once to find an idle line. You can configure multiple hunt groups and the number of rings before the call is routed to the next li ne. Each hunt group must have a minimum of two lines and a unique primary number. There are three hunt sequence options:

What voice do you want to convey when speaking with customers? This may be professional, casual, or even humorous.
Your voicemail greeting can make a positive or negative impression on people. By considering your target audience and tone, you should be able to keep it positive. Length: Don’t make people wait minutes to leave a message. Apologies: If people expect your to be available, apologize for missing their call. Set expectations: Let people know when they may receive a callback, but be realistic. Accuracy: If you change your voicemail for things like holidays, be sure to update it when needed. How do You Set Up a Business Voicemail?