I've just been through this. 1) Skype for business isn't. They have less-than-zero customer service. One example: http://bit.ly/4fYnwz http://bit.ly/4fYnwz. Th

I've just been through this. 1) Skype for business isn't. They have less-than-zero customer service. One example: http://bit.ly/4fYnwz http://bit.ly/4fYnwz. They don't have any support option apart from their forums. And Google Voice is limited to windows PCs. No OS X, Linux, mobile or hardware options. 2) Expensive 3) Damned expensive 4) Hosted VOIP has won for us. We use voipfone.co.uk and I can't say enough good things about them or their services. They have every feature imaginable - including things like voice-mail-to-email and 'Press 1 for Sales'. They use SIP protocols so your hardware and software choices are hardly limited. They use astericks so you can get free trunking to other businesses/locations using astericks. Hosting your own astericks server would be very good too, but I suspect for the scale you're considering, voipfone.co.uk or something similar in your part of the world is the cost-effective way forward. good luck!