check out ring central.
You can be setup and running in a couple of days from the time you place the order...or try it out for 30 days at no cost and move on if you don't like it. You will need a reliable internet connection is the only gotcha, doesn't have to be real fast 1M both ways is sufficient but must be reliable.
I'm testing out their solution now, 10 phones, voicemail, efax, tele and web conference, mobile client (android and ios) desktop client (mac and pc) paging, park, ivr, all for 39.00 per phone/per month. So far it has been working great, phones are polycom 310, 410, or 500.
Each number and phone include a mobile and desktop app, all the other telephony services are standard services that you get with each line.