In both business and private affairs, the word VoIP has become a common phrase to hear spoken in discussions pertaining to communication. Though it is still news to some people, the concept of VoIP was actually developed a little over 30 years ago. We’ll take a quick look at the history of how this technology developed into a major component for telecommunication today.
The birthdate of VoIP isn’t exactly set in stone, but its beginnings can be traced back to as early as 1974. It was actually a by-product in the creation of the internet. Some could even argue that the internet was a spinoff of the creation of VoIP.
ARPANET, or the Internet as it later became known, began with effort that revolved around the concept of digital signal processing (DSP.) One of the first applications for DSP was the transmission of speech. An analog signal was converted to a digital signal and compressed through a kind of early codec then transmitted to another point electronically where it was decompressed and processed as an analog sound. This process was referred to as linear predictive coding or “vocoding” which processes a signal in a similar fashion compared to most sound codecs of today.
This work originally began based on thoughts developed in the late 1960s. The concept derived from real time signal processing of speech that originally surfaced as a topic for many academic papers at the time. Development took place at a steady pace until 1974 when an effort to create more efficient protocols for transmitting data was undertaken by Vint Cerf, Yogen Dalal and Carl Sunshine. Cerf stated in his research titled A Partial Specification of an International Transmission Protocol “The job of the TCP is merely to take a stream of messages produced by one HOST and reproduce the stream at a foreign receiving HOST without change.”
These researchers knew that in order to produce an effective working model for the internet and voice transmission, a standardization for transmitting data between varieties of different machines was necessary. In order for a significant amount of data to be transmitted across a network, TCP was designed to transmit data from end to end with acknowledgment from both ends while also providing sequencing, flow regulation, error amendment and duplication recognition.
Though they had yet to make necessary refinements to the protocol, some success was observed in transmitting voice over an information network. An early network protocol known as NVP was used alongside TCP to place calls across a private network around at a rate of 16 Kb/s. Later calls were placed over ARPANET between the Information Science Institute, Culler Harrision Inc. and Lincoln Labs. Data was only transmitted at a peak of 3.5 Kb/s, so the quality was quite poor. Researchers learned from this experiment that it would be necessary to change the underlying mechanics of the TCP protocol in order to effectively transmit voice.
Over the next four years, several efforts were made to refine TCP because of some flaws that were included in the first incarnation of the protocol. Basically, TCP did not have the ability to actively verify data packets from both end points, so packets received from old transmissions were not distinguished from a new transmission. They appropriately referred to this process as a “three way handshake.” It was 1978 that Cerf and Jon Postel wrote TCP Version 3 Specification that describes spitting the protocol into two more refined protocols.
At this point, work began to split TCP into TCP/IP. Rather than leaving the entire burden of transmission to TCP, IP was spliced from the protocol to handle packet routing. With the creation of IP, TCP was left to handle packet assembly, reassembly (for the purpose of retransmission) and error handling.
The next major component in the development of VoIP was the invention of the UDP protocol. In 1980, this protocol was developed by David P. Reed as an alternative way to transmit data across a network. UDP functions on a layer that works above the IP layer providing a mechanism to transmit data with minimal provisioning. By using UDP, data could be sent in a more real time fashion as UDP doesn’t employ an error checking mechanism. The mechanics of this protocol are found today in protocols used for streaming media as time sensitive material can get hung up when waiting for error checking processes to resolve. This gives favor to marginally decreased quality over a “perfect” communication session.
In 1995, the first VoIP product was released to consumers by VocalTec. The Internet Phone product from VocalTec could be used with a home computer equipped with sound card that could run a mic and speakers. The early days of this technology required those on both ends to configure the application to near identical specifications, unlike today’s VoIP apps that can be used to call other VoIP numbers or landlines.
It is amazing to see how far this technology has come, especially in the past 15 years. Now, VoIP is one of the most utilized methods for communicating and it’s becoming larger as time passes. It will be interesting to see how VoIP will be utilized 30 years from now. Perhaps something new will spin off in the next 30 years, like real time hologram conversations!