The history of unified communications is tied to the evolution of the supporting technology. Originally, business telephone systems were a private branch exchange (PBX) or Key Telephone System provided and managed by the local phone company. These systems utilized analog or digital circuits provided by the phone company in order to deliver phone calls from the Central Office (CO) to the customer. The system, be it a PBX or Key Telephone System, would then accept the call and handle routing the call to the appropriate extension or line appearance on the phones at the customer's office.
The major drawback to this service was the reliance on the phone company to manage (in most cases) the PBX or Key Telephone System. This resulted in a residual, recurring cost to customers. Over time, the PBX became more privatized, and internal staff members were hired to manage these systems. This was typically done by companies that could afford to bring this skill in-house and thereby reduce the requirement to notify the phone company or their local PBX vendor each time a change was required in the system. This increasing privatization triggered the development of more powerful software that increased the usability and manageability of the system.
As companies began to deploy IP networks in their environment, companies began to use these networks to transmit voice instead of relying on traditional telephone network circuits. Some vendors such as Avaya and Nortel created circuit packs or cards for their PBX systems that could interconnect their communications systems to the IP network. Other vendors such as Cisco created equipment that could be placed in routers to transport voice calls across a company network from site to site. The termination of PBX circuits to be transported across a network and delivered to another phone system is traditionally referred to as Voice over IP (Voice over Internet Protocol or VoIP). This design required special hardware on both ends of the network equipment to provide the termination and delivery at each site. As time went by, Siemens, Alcatel-Lucent, AltiGen, Cisco, Nortel, Avaya and Mitel realized the potential for eliminating the traditional PBX or Key System and replacing it with a solution based on IP. This IP solution would be driven by software only and thereby do away with the requirement for "switching" equipment at a customer site (save the equipment necessary to connect to the outside world). This created a new technology which is now referred to as IP Telephony. When referring to a system that does not utilize any legacy PBX or Key System but rather IP-based telephony services only, it qualifies as an IP Telephony solution.
With the advent of IP Telephony the handset was no longer a digital device hanging off a copper loop from a PBX. Instead, the handset lived on the network as another computer device. The transport of audio was therefore no longer a variation in voltages or modulation of frequency such as with the handsets from before, but rather encoding the conversation using a CODEC (G.711 originally) and transporting it with a protocol such as the Real-time Transport Protocol (RTP). When the handset is just another computer connected to the network, advanced features can be provided by letting computer applications communicate with server computers elsewhere in any number of ways; applications can even be upgraded or freshly installed on the handset.
When considering the efforts of Unified Communications solutions providers, the overall goal is to no longer focus strictly on the telephony portion of daily communications. The unification of all communication devices inside a single platform provides the mobility, presence, and contact capabilities that extend beyond the phone to all devices a person may use or have at their disposal.[3]
Given the wide scope of Unified Communications, there has been a lack of community definition as most solutions are from proprietary vendors. Since Mar 2008, there are several open source projects with a Unified Communications focus such as Druid and elastix, which are based on Asterisk, a leading open source telephony project. The aim of these open source Unified Communications projects is to allow the open source community of developers and users to have a say in Unified Communications and what it means.
IBM entered the unified communications marketplace with several products, beginning in 2006 with the updated release of a unified communications middleware platform, IBM Lotus Sametime 7.5[4], as well as related products and services such as IBM WebSphere Unified Messaging, IBM Global Technology Services - Converged Communications Services, and more. In October 2007, Microsoft entered the Unified Communications market with the launch of Office Communications Server[5], a software-based solution running on Windows. In March 2008, Unison Technologies launched Unison[6], a software-based unified communications solution that runs on Linux and Windows.
In May 2010, the Unified Communications Interoperability Forum (UCIF) was announced. UCIF is an independent, non-profit alliance between technology companies that creates and tests interoperability profiles, implementation guidelines, and [best practices] for interoperability between UC products and existing communications and business applications. The original founding members were HP, Juniper Networks, Logitech / LifeSize, Microsoft, and Polycom[7]. Other members are Acme Packet, Aspect, AudioCodes, Broadcom, BroadSoft, Brocade Communications Systems, ClearOne, Jabra, Plantronics, Radvision, Siemens Enterprise Communications, and Teliris.[7][8]
As the buzz about cloud computing has resonated strongly in 2010, there is some debate about whether Unified Communications hosted on a enterprise's premise is the same thing as Unified Communications solutions that are hosted by a service provider[9]--or UCaaS (UC as a Service). This may be mostly a marketing distinction as all of these approaches properly fall under the single umbrella term of Unified Communications.
