Explain Your Return Call Policy: In your after hours message for the medical office, be sure to state your return call policy for voicemail response. By giving callers an estimate of when they can expect a return call from someone in your office, you can eliminate multiple phone calls from the caller, as well as reduce work for your staff members.
You can also make use of a 3rd party option and use a crowdsourcing professional voicemail greeting provider such as Fiverr to record your voicemail greeting. Fiverr is flexible, fast and affordable and at just $5, you have the option of choosing between hundreds of professional voice-over actors who can record your script. You can also find professionals who can record voicemail greetings in various languages, accents, etc. at very affordable prices and deliver the recording within 3 working days or less.

As of Oct. 16, 2013, the FCC interpreted “prior express consent” as requiring a signed, written agreement, specifically agreeing to receive text messages or telemarketing calls and voicemails using a pre-recorded voice.
After you have created your Voice Mail entry, you can assign it to any of your DID from your main portal. Please refer to DID Numbers -> Manage DID -> Edit DID -> Voicemail. Also under the same screen you can set the Ring Time (The maximum amount of time a call to your DID can stay in "Ringing State" before we cancel the call to no answer). Please note that 30s equals to 6 rings.