To clear any customers doubts or expectations, make sure to mention on your voicemail when you’ll be available. Don’t say that you will “try” to return their call. Instead, offer them a realistic timeframe in which they can expect their call to be returned, so they know what to expect - whether it will take you 24 hours or a week to get back to them. This will eliminate your customer’s worries about your timeliness and encourage them to wait for your reply instead of heading over to your competitors.
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.

Really think about it – You’re out of the office, it’s after business hours, or you’re otherwise indisposed, whatever the case may be, your voicemail is now tasked with representing you (and/or your company). No pressure, right? Your voicemail message is a platform that represents you to callers; therefore it’s ABSOLUTELY crucial that your message is perfect.
In an ideal world, voicemail would be unnecessary. There would always be someone available to take customer calls and no one would complain about their calls not being returned and/or rejected. But of course, this perfect world isn’t possible. That’s why it’s important to give your callers options when you are unavailable. For example, aside from leaving a message, callers can also choose to listen to some relevant information about your business (such as a list of your services, your address, directions, hours of operation, and more).