If you’re ready to go the professional direction, congratulations! Here are some websites you can use to hire a service to record your greeting.
When you hear the Dial Tone, call into your landline or office voicemail box. The rule of thumb is when you hear the Voicemails Forever dial tone, then follow your phone's instructions to listen to your voicemails remotely. This will vary from carrier to carrier and phone to phone. You may need to call your phone networks customer support for updated instructions.

9. Update Your Greeting Frequently. Many of the things that can make your voicemail great, also require that you update it pretty regularly. Information like deals you’re running, when you’re away, and who to contact while you’re out can take your greeting to the next level, but they’re obviously time sensitive.
I like to say my phone number very early so the person can hear it again quickly by starting the message over and does not have to listen to your entire message again to hear the number. But do repeat your telephone number at the end of the message at least once and speak very s-l-o-w-l-y so the person can write it down as they listen. If you don't get a response to your first voicemail, don't hesitate to record a similar message once a week for two or three weeks. This sounds a bit excessive, but my experience has been that if there is even the slightest chance of meeting someone now or even in the near future, this kind of message will get their attention.