Displays the name and telephone number of the incoming Call Waiting caller, provided they are not blocking that information. This feature requires a Caller ID compatible telephone or display device.
So before you begin shopping, start with a clear assessment of exactly which functions you need. Don't get caught up in a more-functions-is-necessarily-better mindset when comparing systems. Also, take advantage of the trials and demos offered by some companies to get a firsthand feel for exactly how user-friendly a system is.

I have a confession to make: I haven’t recorded a new voicemail greeting since 2014. In the past four years, I (hopefully) have become more articulate, poised, and self-assured. But hear my voicemail recording, and you’d think I was still new to the work world, a little unsure of myself — and probably not an authority. Obviously I need toupdate it. And if you haven’t changed your voicemail greeting in over a year, you’re likely in the same boat. After all, a professional voicemail recording boosts your credibility, makes you seem more competent, and encourages whoever’s listening to it to continue the relationship. A relatively unprofessional one — like mine, for instance — does the opposite: It encourages prospects, recruiters, and potential connections to run in the other direction. With that in mind, I’ve written 18 unique voicemail greetings for every situation. Pick your favorite, practice a few times, then record your new voicemail.
06Hi, you’ve reached the offices of [your company/name]. I will be out of the office between [dates] and [date]. You can reach me on my private cell [your number] if this is an emergency. Alternatively, you can call me when I get back to the office or leave a brief message.