If your company is planning a migration from legacy PBX to VoIP, you have a choice of at least three paths.
One is to do a wholesale conversion, selling or writing off the legacy system.In these cases, some legacy hardware sometimes is kept around for emergencies.
Another choice is to convert locations gradually. For a company with several branch offices, that might mean keeping legacy PBX in place in some offices, but going VoIP in others. To put it another way, a staged rollout.
Your third choice is to build a "bridge," acquiring equipment that can handle both VoIP and PBX.
Enterprise IP Telephony: Premises and Hosted-Service Equipment and Trends, a new report from ABIResearch, discusses the pros and cons of each alternative, and calls the latter choice "common."
That's what they say. What say you? Let us know in a TalkBack.