The reason is simple. There is no point in fixing something that has been working. Imagine that an enterprise that has already paid ten of thousands of dollars in laying out voice cables, building up the voice infrastructure, buying PABX equipments and finally deploying telephone that is capable of PABX functions. And that particular enterprise has been running such a system without any problem for a long time. It would have to have a VoIP salesman that has guts made of steel to try and convince that particular enterprise to forget all about their PABX system and embrace VoIP totally.
In an e-mail fashioned interview, Ng Kai Wa, CEO and co-founder of InnoMedia Pte Ltd commented that PABX will gradually evolve to embrace VoIP as a platform for more efficient delivery of voice and data over one LAN network. Similar feature that one would find on a traditional analog PABX will be available on such IP-PBX. Moreover, sharing the same homogenous IP network for data and voice enables more services and functions that are traditionally not easily available on a PABX. For example, integrated CRM functions for handling customer calls, unified messaging over the same IP network, etc.
Kishore Sanagapali of AT&T Global Network Services shares a similar view. According to him, if PABX were being referred in the traditional way as one would define today, (i.e. an external switching box dedicated for voice traffic) then VoIP will take over PABX. However, he maintains that the function of PABX will exist somewhere in the network - for example, it may exist as an IP telephone (soft phone) or it can be integrated into the IP host (soft PABX) within the branch.
On the contrary, Mitel Networks has a bolder statement to make. “Yes, the PBX will be gradually taken over by VoIP. While still in its infancy, VoIP provides enterprise with unparalleled opportunities for network integration and value-added applications and devices that harness the power of a company's resources.” Jon Carvill, Mitel Networks. “With the advent of intelligent applications and devices enterprise users will be confronted with possibilities never before imagined on the traditional PABX.” He further added.
It looks like regardless of whether the will be a hybrid of PABX and VoIP or a bold move to a true VoIP system, there is no denying that VoIP will be here to stay and the future of corporate communication will be changed.