Supper cool bonus is that SIP trunks are no bound to a location. SIP trunk gave you ability to be free, be not bound to any location. Moving office is rising no problem, your services and numbers go with you. No more complicated forwarding orders or letterhead changes. You can even add regional and international office numbers to allow client customers to avoid long distance charges.
As more and more adults are skipping landlines, start-ups are skipping costly PBX systems and wiring. Dedicated desks and their associated phones are becoming more outdated.