Phone Systems have evolved over the last 10 years. With the death of the traditional PBX and the new VoIP movement businesses have more reasons to upgrade and more feature sets to choose from. I previously managed the IT department for a small company that relied heavily on the phone system.
They purchased a (at the time) a state of the art system and spent a big chunk of change thinking it would last them forever. Fast Forward 10 years and that same system that cost them hundreds of thousands of dollars is now worth 30K (if they found a sucker on the street) and they were spending thousands of dollars every month on maintenance for the ancient piece of equipment sitting on the wall. They were stuck with a dinosaur and were quickly falling behind their competitors.