Does your organization have a witty catchphrase or slogan? If so, use that to your advantage. Here is one that could be tailored towards a custom software company:
Crafting the perfect voicemail greeting is not as easy as it may seem at first glance, depending on the type of greeting: Business, funny, professional, formal, and informal, you need. Below, we’ve included some tips in creating the perfect voicemail greeting. Go over them, then when you complete your final voicemail script, revisit these tips again to make certain you’ve covered all the bases.

Humor also leaves a lot of room for misinterpretation—which subsequently weakens sincerity and authority. A caller can be very turned off by merely misinterpreting your joke. Why take this risk? Additionally, this could even cause callers to question your character. Say, for example, the president of a company’s mobile phone voicemail greeting was funny. What’s to happen if the caller didn’t like or get the joke? What if they found it offensive? Another scenario is that a caller is reaching out to you for the first time—i.e. they have no idea regarding your personality. What next? The point is, with this type of greeting, humor is bound to be more divisive so just avoid it altogether. c. Poorly Pacing Your Message and Bad Time Management: Don’t speed through your message. Speak clearly so callers know what to include in their message and when to leave the message. At the same time, don’t drag your message out. No one wants to sit through a diatribe. Just get to the point clearly.
Part of my issue is that I really probably do need the NHS and local gov't to be able to leave me voicemail (not least because the NHS isn't set up to deal with e-mailing patients, at least not where I am at the moment), but for pretty much everyone else EVER I will call them back much sooner if I don't have the mental hurdle of voicemail first (where the fundamental difference is that by and large the NHS & gov't don't give a shit if I call them back...). So uh. Yeah. :-/