The phone you use to record your greeting – and your surrounding – can turn your carefully scripted greeting into an unprofessional mess. Background noise is terribly distracting, so choose a quiet room or parked car to make your call. Landlines, or a “wi-fi enabled” cellphone call, can provide much better connection quality than a standard cellphone. If you must use a cell phone, be sure to use a high-quality headset for the best clarity.
Yes, you can be charged. This depends on the service. For example, Spectrum’s Voice Residential Services Price Guide charges $3.95 for voicemail.

12. “Hello, you’ve reached the Customer Support department at [company name]. We are unable to take your call at the moment. We know your time is valuable so instead of placing you on hold, let us call you back! Please leave your name, phone number, the reason for your call, and two different times that are convenient for you to receive a call back from us. Thank you!” Get a better idea of your caller’s schedule by asking them for a few different times you can call back. Their time is important, too!
Recording voicemail greetings for your business or personal life requires a separate list of priorities, because they are being used for two distinct purposes and will be heard by two very different types of callers. I have a friend with two cell phones - one for work, and one for personal calls - and if you call both lines, you would never know it's the same person.