This article originally appeared in the October 2010 issue of Unified Communications magazine

Are the days of PBX (News - Alert)/UC appliances numbered? Will UC and PBX functionality reside in the data center, embedded within network infrastructure, or within PBX appliances? Several technology trends are now converging that will radically change the name of the game for IP telephony, unified communications and IT infrastructures.

First, and probably the most profound, is computing technology. After more than half a century Moore’s Law is still operating. The most recent crop of 4-12 core 64-bit microcomputers, combined with the improved reliability of IT server operating systems and network services (Windows Server constitutes 74 percent and Linux 21 percent of the market, according to IDC (News - Alert)), make it possible to run PBX and UC applications in commercially available server platforms within a data center. With the recent ability of virtual machine operating systems to support RTP traffic, these applications can now run in VM’s within the data center or as a cloud service.

Second is open IP telephony protocols, primarily session initiation protocol, which after only 10 years in existence is now supported by most PBXs and UC applications. SIP has made interoperable IP telephones and legacy telephony interface gateways, SIP-aware firewalls and application layer gateways of every variety readily available.

Third, thanks to the evolution of Ethernet LANs over the last 45 years and fiber optic transmission technology over the last 40, more bandwidth is available both in customer LANs, and for access to carrier networks. The capacity of a 1 gigabit Ethernet LAN (68gbps switching fabric) now far exceeds the largest TDM central office switch matrix (about 16gbps for a 128K port DS-0 matrix). Campus Ethernet switch fabrics support almost a terabit per second of throughput. Carrier network access provided by the various FTTx technologies, GPON, and active Ethernet, provide rates from a few megabits per second up to 1gbps, all more than enough for SIP trunking to supplant telephony trunks. With all this bandwidth, RTP media sessions, including HD video, can now easily be transported within business LANs and intra-networks.

Fourth is the more recent introduction of cloud computing, which expands the options available for data centers.

All four of these technologies are readily available from many competing vendors using open and industrial standards. Technology advances in this competitive environment constantly drive down price. What effect are these trends having on IP telephony and UC applications?

PBX and UC appliances are no longer required. Why? The three main hardware components of PBX and UC appliances, central processing, telephone and trunk interfaces, and matrix switching, are provided by readily available commercial products: servers, SIP gateways and IP networks. Rather than being deployed as proprietary appliances on a customer’s premises, PBX and UC applications can now be deployed in servers or VMs within the data center, or by a cloud service provider. Legacy telephony and trunk interfaces and associated functions like tone detection, fax modems, etc. (that require DSP) are provided by SIP gateways. A TDM switching matrix and telephone interfaces are no longer required, as these functions have been subsumed into the IP network with the advent of IP telephones.

Free of the requirements of special hardware and connected only by the IP network, PBX and UC applications now have the freedom to reside in data centers alongside other line of business applications. Integration of these applications with OS-based network services that provide common user administration, authentication, delegation of authority and automatic server selection, becomes easier, much like other LOB applications. This allows IT administrators to manage PBX/UC users and servers using their existing network operating system directory services such as Microsoft (News - Alert) Active Directory.

The advantages of integrating PBX and UC applications into the data center such as common administration and management by IT staff; single user management, authentication, and delegation of authority (and hence single user log-in); common server hardware, OS and their maintenance; and speed and ease of deployment and moves, adds and changes make integration into the data center a compelling proposition. Of course, you have to have an IT infrastructure to gain these advantages.

So, businesses that have IT are going to be affected by these trends over the next few years.  Eventually, only businesses that don’t have IT will have a need for more traditional PBX/UC appliances. The divide between businesses that have IT and those that don’t is typically somewhere between 50 and 100 users. So, many small businesses that don’t have IT will continue to use PBX/UC appliances, while medium-sized businesses  and enterprises will inevitably be caught up in the trend to move PBX/UC functionality into their data centers.  Branch offices in larger organizations could still see a demand for appliance-based PBX/UC functionality depending on how IT is deployed into the branch offices.

How should your respond to these trends? Avoid big iron PBXs and look for vendors that provide software-based SIP PBX/UC applications that will fit into your data center with common user management. If you need an appliance, then look for vendors of all-in-one PBX/UC appliances for under 100 user organizations and branch offices that can be upgraded by the addition of UC services in servers within a data center setting.