Let’s Talk About VoIP and Cisco
An introduction to VoIP technologies and Cisco’s role in it.
By: Jessica Anderson, Sr. Voice Engineer at Aston Technologies
What is VoIP?
VoIP stands for Voice over Internet Protocol. It is a technology that allows us to place phone calls over an internet connection. This can also be referred to as IP telephony. IP telephony relies on digital interfaces to carry phone calls.
stop here and do a little history lesson. I want you to truly understand what VoIP is and how it works and for that to happen, we have to go back in time.
How VoIP Started
Simply put, audio communication is information that is transmitted in a form that can be heard. Whether it’s the sound of a whistle, you talking to a friend, or music playing through your speakers, we communicate through audio in almost every aspect of our lives.
The discovery of electricity propelled the way audio communication was used. In the 1830s the telegraph system was created. This system worked by sending electrical signals over a wire. Electrical signals were used to transmit tones in a pattern. We call this Morse Code and it’s still used today.
The telegraph initiated a way for voice audio to be sent over the same electrical wire. Toward the late 1870s, the first telephone exchange opened. It involved an operator taking an incoming call and manually connecting it through its intended destination.
This worked well until operators started catching what we call “the common cold” and finding a replacement was not easy, especially due to the training process. Thus, the automatic telephone exchange was created. It contained many electromechanical switches that were controlled by dialed pulses. This is what we call circuit switching.
The term Plain Old Telephone Service (POTS) comes into play here where it describes a basic telephone service that transmits an analog voice signal over copper wires. It’s also worth mentioning the term PSTN or Public Switched Telephone Network, is a combination of telephone networks used worldwide which help telephones communicate with each other.
As technology advanced, so did circuit switching and for businesses, analog (one-to-one) connections got pricy. Thus, the Private Branch Exchange (PBX) was introduced. It operates in the same fashion as the automatic telephone exchange however its purpose is to route calls exclusively within a business. The concept is to share a small number of phone lines across a large number of phones. PBX systems are typically suited for businesses that have over a hundred employees.
Telecommunication companies started to gradually convert their phone infrastructures from analog to digital and Integrated Services Digital Network (ISDN) was designed as a way to migrate that transition.
Now you’re probably wondering why the transition from analog to digital. Well, the quality of an analog voice signal gets worse as it travels through switches and there’s no way to improve the quality. Digital signals can travel further than analog. Also, analog wires are costly and are not portable.
Now back to ISDN, ISDN is similar to POTS however analog signals are converted into a digital format before it’s sent across the wire and then the signal is converted back into analog at the receiving phone.
As the internet grew in popularity, the Internet Protocol merged with PBX and the next generation of business communications was born.
By the late 1990s, the first IP PBX service became available and it supported a new technology that allowed phone calls to be placed over the internet called Voice over Internet Protocol (VoIP).
The best benefit of the IP-based system was virtualization; A company didn’t need to rent or purchase computerized switchboards but instead use an internet connection to transmit their data.
VoIP became very popular because network bandwidth and audio compression algorithms (reducing file sizes) were too restrictive so the introduction of highspeed and broadband internet made VoIP a reality. It reduced communication cost, cabling costs and added a bunch of voice-internet capabilities.
Meet Marian Croak
Marian Croak, Ph. D. is credited for creating the technology called, Voice Over Internet Protocol.
If it hadn’t been for her work at AT&T, along with her insistence on replacing wireline phones with IP, we would not be making calls or holding video conferences on the internet today. Her work and that of her colleagues have laid the foundations of modern phone communications through VoIP.
VoIP and Cisco
In 1997 Selsius Systems came out with one of the first IP PBX systems consisting of a line of IP phones, VoIP gateways, a server-based call control application called Selsius Call Manager, and many voice applications such as voicemail. One year later Cisco acquired Selsius and renamed their call control application to what we now know as Cisco Unified Communications Manager (CUCM).
Cisco Unified Communications (UC) is Cisco’s product for Voice over Internet Protocol (VoIP) communication. This set of products used to be called IP Telephony (IPT). It integrates voice, data, video, and mobility products and applications and represents a paradigm shift like one of the telegraph inventions.
CUCM processes inbound voice traffic from your gateway via the PSTN (Public Switch Telephone Network) and outbound voice traffic to your gateway to the PSTN.
The connection from your voice gateway to the PSTN is made using a circuit.
CUCM sometimes referred to as Cisco Call Manager, is a popular call management software that is installed on a Linux platform, as opposed to Windows. Once installed, administrators access the call manager’s graphical user interface (GUI) by entering the domain name or its IP address in the URL bar in a web browser.
CUCM comes pre-packaged with a whole host of functionality including:
- Being able to roll calls from one phone to another
- Ability to put a call on hold
- Ability to transfer the call to another destination
- Configurable speed dials
- Enable users to move a phone to another location and retain their profile
- Ability to forward calls to any destination
- And many more…
Cisco continues to be the leader in IT solutions as VoIP technology continues to grow.
