While companies aren’t ripping out their PBXs for IP telephony systems en masse, a report from ABI Research says most enterprise voice systems purchased over the next several years will be IP-based.

The research firm says IP PBX seat shipments (licensed end-user ports on an IP phone system) will grow from 3.2 million in 2003 to 26 million by 2006. ABI cites improvements in IP PBX and IP phone features and stability, and interest in deploying converged voice/data applications in corporations, as the growth drivers of IP PBXs.

ABI also says companies will adopt fewer hybrid voice systems, where PBXs are IP-enabled with gateway technology or IP PBXs are integrated with existing circuit-switched phone networks. The research firm also says that by 2006, 90 percent of all new IP phone systems shipped will be 100 percent IP, as opposed to mixed circuit-switched/IP equipment.