Basic Telecom Terminology

The Telecom world is full of abbreviations and odd words. It can be confusing at times. Not any more! We’ve compiled a handy list of basic Telecom terminology for you. Just click through the menu items below and you’ll be well on your way to a more informed perspective.

ACD (Automatic Call Distribution)

ACD is used to deliver calls to contact center agents based on user inputs or pre-defined rules including skills-based routing. 

ATA (Analog Telephone Adaptor)

An ATA is a hardware device that connects analog (non-IP enabled) telephones, PBX systems, fax machines, door alarms and similar devices to digital systems or an internet-based telephony network. ATAs are used to connect legacy hardware to more modern telecommunications equipment.


Bandwidth is the amount of data that can be transmitted over a communication line in a specified period. It is described usually in bits per second (bps) or bytes per second for digital devices and in cycles per second, or Hertz (Hz) for analog devices. 

Broadband Telephony

Broadband telephony refers generally to voice calls that are transmitted over the internet, rather than traditional telephone lines. The term is commonly used interchangeably with VoIP, internet telephony or IP telephony. 

CDR (Call Data Record)

A stored database record containing data about a specific call. A CDR contains details such as the called and calling parties, originating switch, terminating switch, call length, and time of day.


Codec, which stands for coder-decoder, converts an audio signal (your voice) into compressed digital form for transmission (VoIP) and then back into an uncompressed audio signal for replay. It’s the secret sauce of VoIP. Different codecs have different levels of compression. The highly compressed signals require less internet bandwidth, while less compression is associated with better voice quality. 

CTI (Computer Telephony Integration)

Software that integrates voice communications systems with computers for contact center and office automation applications. 

DID (Direct Inward Dialing)

A method of directly dialing the number of a IP Phone or a telephone attached to a PBX without routing calls through an attendant or an automated attendant console. 


E911 stands for Enhanced 911. This service allows customers to set any physical address as the one to be relayed to emergency dispatchers when 911 is dialed. It also ensures that calls to 911 are routed to the nearest Public Safety Answering Point. 

IP (Internet Protocol)

Internet Protocol is a standard that defines the way that data is transmitted between the source device and the destination. It is the network layer protocol in the TCP/IP communications protocol suite. Telecommunications hardware that is designed for use over the internet is commonly called “IP enabled.” IP enabled phones may be referred to as “SIP Phones” or “VoIP Phones.” 

IVR (Integrated Voice Response)

An application that provides full-featured integrated voice response capability to answer inbound calls, perform database lookups, re-direct calls automatically, etc. 


Jitter is used to describe a short fluctuation in the transmission of a voice signal. In SIP trunking, it may result from an abrupt variation in signal characteristics, such as when a data packet arrives either ahead or behind a standard clock cycle. 


Latency is the time between the moment a voice packet is transmitted and the moment it reaches its destination. This delay may be in nanoseconds, but it is still used to judge the efficiency of networks. Latency in SIP trunking can lead to poor quality calls. 

LEC (Local Exchange Carrier)

The local phone company responsible for delivering calls within a local area. 

PBX (Private Branch Exchange)

A PBX is the hardware and software that comprise a business telephone system.  Internet enabled PBX technology is called IP PBX (Internet Protocol Private Branch Exchange). 

POTS (Plain Old Telephone Service)

A single phone line and a single phone number. Home phones and dedicated fax lines are good examples of POTS. 

PRI (Primary Rate Interface)

PRI is a physical connection to the PSTN over a dedicated line that only serves voice transmission. Traditional business telephone systems leverage PRI. 

PSTN (Public Switched Telephone Network)

The PSTN is the combination of local, long-distance, and international carriers that make up the worldwide telephone network. 

QoS (Quality of Service)

QoS is a router setting that prioritizes voice traffic over data traffic. This improves the quality of internet-based telephone calls. 

SIP (Session Initiation Protocol)

Session Initiation Protocol (SIP) is an industry standard application-layer protocol that can initiate, manage and terminate Peer-to-Peer (P2P) communications and multimedia, including voice, video, email and instant messaging. 

SIP Phone/IP Phone

The terms SIP phone and IP phone refer to desktop handsets that are IP enabled, or capable of processing packets of voice data that pass over the internet between users. 

SIP Trunking

SIP Trunking is a Voice over IP phone solution that uses a trunk to connect an IP-enabled PBX or VoIP Gateway to the internet. SIP Trunking uses cloud-based technology to take advantage of shared lines, such as a company’s existing internet connection, to combine voice and data onto one network. 

SIP Channel

A SIP channel represents one digital connection to the PSTN. SIP trunks can have an unlimited number of channels, with each channel representing one concurrent telephone call. 

Soft Switch

A soft switch is the software equivalent of a physical telephone switchboard. Internet-based telephony and even some traditional telecommunication networks use soft switches to manage the connection of phone calls. 


A softphone (also known as a soft client) is a software program for making telephone calls over the internet using a computing device, rather than a traditional telephone handset. The application can be run on a desktop PC, laptop, tablet or cell phone. 


Telephony refers to any technology involving the development, application, and deployment of telecommunication services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is intimately linked to the invention and development of the telephone. 

VoIP (Voice over Internet Protocol)

Voice over Internet Protocol (VoIP) is a group of technologies that work to deliver voice and other multimedia sessions over Internet Protocol (IP) networks, most commonly the internet.  SIP trunking is one method of achieving VoIP, others include the public Internet and private point-to-point networks.