5. You have reached [your business]. We are currently closed. Our normal hours of operations are from [hours] [days]. We are closed on [days]. Please leave us a message with your name and number and we will return your call when the office reopens. You may hang up after leaving your message or press the [key] for additional options. Thank you for calling.
The simple truth is that you need to be more aware of what you’re leaving for other people to hear. Sure, this doesn’t always register as a priority for users, but it’s never too late to reassess your greeting. a. Reading/Speaking in the Imperfect Tone: Tone is absolutely everything. Users don’t want to come off as being too nice, as it sounds insincere, or being too terse, as it can be interpreted as being rude. That being said, striking the right balance is absolutely essential. Your greeting exists as its own entity, and therefore, it should NOT rely on callers’ familiarity with you. Instead, it needs to appeal to the masses. As such, your inflection, i.e. the way you state your name and directions, needs to be both welcoming and firm. b. Injecting Humor & Insincerity: While humor/light heartedness can be welcoming, it can also convey a sense of informality, insincerity, and ultimately unprofessionalism. Why, because you’re not there to lend your humor or to contextualize. Instead, you’re assuming the caller has a working knowledge of your personality to ground the message. Though this might not sound like it’s all that terrible—it can be detrimental. As stated above, one should NEVER rely on a caller’s familiarity with you. Instead, aim to appeal to the masses. Humor is ultimately subjective, meaning not everyone has the same tastes; therefore, someone is bound to be turned off by a quirky or off-color remark. While implementing a light-hearted or even tongue and cheek tone can work, it’s just a really bad idea.

It's as much a truth with residential phone service as it is with business communications, though those numbers are much lower. Voice over Internet Protocol (VoIP) phone service provider Vonage reported in April that voicemail deposits among its residential customers had dropped by 8 percent since October 2013, and retrieved messages were down 14 percent.
Avoid too many promises – Avoid promises you can not keep – in this case, dates and timeframes for when you will 'definitely' return calls.