VoIP Terminology Defined: The Ultimate A-Z Dictionary for Business Communication

Unlock Your Communication Potential: A-Z Guide to VoIP Terminology

In the world of business communications, acronyms and technical jargon are everywhere. Whether you are migrating your office to the cloud or optimizing a large contact center, mastering VoIP Terminology is the key to making informed decisions and avoiding costly errors.

At Seed Telecom, we believe in empowering our clients. This comprehensive A-Z dictionary demystifies the language of Voice over Internet Protocol (VoIP), transforming confusing technical terms into actionable knowledge. Use this guide to ensure you are speaking the same language as your provider, verifying call quality, and maximizing the power of your phone system.

The Definitive A-Z Dictionary of VoIP Terminology

A

• ACD (Automatic Call Distribution): A sophisticated system that intelligently routes incoming calls to the most appropriate available agent based on predefined rules, such as skill set, call volume, or idle time. Essential for contact centers.
• AHT (Average Handle Time): A key call center metric measuring the average time an agent spends on all parts of a call, including talk time, hold time, and any after-call work. Lower AHT generally indicates higher efficiency.
• ATA (Analog Telephone Adapter): A hardware device that converts the analog voice signal from a traditional phone or fax machine into digital packets for transmission over a VoIP network. It acts as a bridge for legacy devices.
• Audio Conferencing: A feature that allows three or more people to engage in a telephone call simultaneously, typically managed by a Conference Bridge (physical or virtual).
• Auto Attendant (AA): A feature, often called a virtual receptionist, that answers incoming calls with a pre-recorded greeting and presents the caller with a menu of options (e.g., “Press 1 for Sales”) to self-direct their call.

B

• Bandwidth: The maximum volume of data that can be transferred over an internet connection in a specific amount of time (usually measured in Mbps). Insufficient bandwidth is the leading cause of poor VoIP quality.
• BLF (Busy Lamp Field): A feature, typically seen as lighted buttons on a VoIP Phone  or softphone interface, that displays the real-time status (busy, ringing, available) of other extensions within the organization.
• BYOD (Bring Your Own Device): A policy allowing employees to use their personal mobile phones or computers to access corporate VoIP and communication services via a Softphone app, enhancing flexibility.

C

• CDR (Call Detail Records): A detailed log of all phone call information processed by the phone system. CDRs include data points such as the time of the call, duration, originating number, destination number, and, often, billing information.
• CLI (Caller Line Identification): Commonly known as Caller ID. It is the service that transmits the calling party’s phone number to the recipient’s phone. If you need further clarification this article The Ultimate Guide to CLI in Telecom: What It Is, How It Works, & Why It Matters is for you. 
• CNAM (Caller ID Name): The feature that displays the name associated with the calling number, which is pulled from specific third-party databases (often regional).
• Cloud Communications: A broad term referring to any voice, video, or data communications service where all applications, switching, and storage are hosted by a third party outside the customer’s premises and accessed over the Internet. Synonymous with Hosted PBX.
• Codec (Coder-Decoder): The technology (software or hardware) used to compress and decompress voice data packets for efficient transmission over the Internet. The choice of Codec (e.g., G.711 or G.729) directly affects both call quality and bandwidth usage.
• Compression: The mathematical process of reducing the size of digital voice data to optimize the amount of information that can be transmitted in a single packet, thus saving bandwidth.
• CTI (Computer Telephony Integration): Any technology that allows phone systems to interact with computer systems, most commonly used to integrate a phone system with a CRM database to enable features like “screen pops” (automatically displaying customer records when they call).

D

• DHCP (Dynamic Host Configuration Protocol): A network protocol that automatically and dynamically assigns an IP Address and other configuration parameters (like the DNS server) to devices on a network.
• DID (Direct Inward Dialing): A service that allows external callers to dial a unique, individual phone number (or extension) directly, bypassing the main switchboard or operator.
• DND (Do Not Disturb): A common phone feature that temporarily suppresses all incoming calls, sending them directly to voicemail or forwarding them to another extension, depending on the system configuration.
• DSL (Digital Subscriber Line): A technology used to transmit digital data over traditional copper telephone lines. While widely available, its bandwidth capacity is often inferior to modern fiber connections for demanding VoIP traffic.
• DTMF (Dual Tone Multi-Frequency): The standard “Touch Tone” sounds produced when keys are pressed on a phone keypad. IVR systems and automated attendants use these tones to select options.

E

• Echo Cancellation: A process or algorithm used to detect and eliminate acoustic echo—where a caller hears their own voice repeated back—which is typically caused by variations in Latency.
• E911 (Enhanced 911): The emergency service feature required for modern VoIP systems that automatically transmits a caller’s registered physical address and callback number to the emergency dispatcher, ensuring quick response times regardless of location.
• Encryption: The process of converting digital data into a code (cyphertext) to prevent unauthorized access. For VoIP, SRTP is commonly used to encrypt voice packets, ensuring call confidentiality.
• Endpoint: Any device that a user utilizes to connect to the VoIP system and make/receive calls. Common endpoints include a physical VoIP Phone, a Softphone, or an ATA.
• EWT (Estimated Wait Time): A key call center metric that predicts and communicates how long a new caller in a Call Queue will wait before speaking to an agent.

F

• FMC (Fixed Mobile Convergence): The integration of office (fixed) phone lines with mobile devices, allowing seamless access and use of desk phone features (like the office number) from a mobile application.
• FOC (Firm Order Commitment): A date provided by the “losing” carrier during a Number Porting request, indicating the specific date and time they will release a phone number to the “winning” carrier (like Seed Telecom).
• Full Duplex: The ability of two parties in a communication session to send and receive information simultaneously, mirroring the experience of a face-to-face conversation. VoIP systems are designed to operate in full duplex mode.
• Firewall: A network security system that monitors and controls incoming and outgoing network traffic based on predefined security rules. Proper firewall configuration is crucial to prevent VoIP traffic from being blocked.

H

• Hosted PBX: A Private Branch Exchange (PBX) system that is owned, hosted, and entirely managed by the VoIP service provider in the cloud. This eliminates the need for the customer to purchase or maintain on-site hardware.
• Hunt Group: A configuration of multiple phone extensions set up to receive an incoming call sequentially, simultaneously, or randomly until an available line picks up. Used to distribute call volume across teams.

I

• IP Address (Internet Protocol Address): A unique numerical label assigned to every device (endpoint, server, router) connected to a computer network that uses the Internet Protocol for communication.
• IP PBX: An on-premises PBX system that uses the Internet Protocol to route calls. Unlike a traditional analog PBX, it handles voice traffic as data packets over the local network.
• ISP (Internet Service Provider): The company that provides internet access to a business or home. The quality and reliability of the ISP directly impact the performance of a VoIP system.
• IVR (Interactive Voice Response): An automated phone system that interacts with callers, gathering information and directing them to the appropriate destination via a pre-set menu and voice or keypad input.

J

• Jitter: The variation in the time delay between the arrival of consecutive voice data packets. High Jitter causes audio to sound fragmented, distorted, or “choppy.”
• Jitter Buffer: A mechanism (hardware or software) that collects incoming voice packets and stores them briefly before playing them back at a steady rate, helping to mitigate the adverse effects of Jitter.

L

• LAN (Local Area Network): A computer network that interconnects devices within a small geographic area, such as an office building or campus. VoIP phones connect to the corporate LAN.
• Latency: The delay in the time it takes for a data packet to travel from the source to the destination. VoIP requires low Latency (ideally under 150 milliseconds one-way) to maintain a natural conversation flow.
• LNP (Local Number Portability): The regulatory process that allows a business to keep its existing geographic telephone number when changing to a new service provider, such as migrating from a PSTN line to a VoIP SIP Trunk.
• LOA (Letter of Authorization): The legal document required when performing Number Porting (LNP), granting the new service provider (Seed Telecom) permission to act on the client’s behalf to transfer the number.

M

• MOS (Mean Opinion Score): The most common metric for measuring perceived voice quality on a scale of 1 (unacceptable) to 5 (excellent). A score of 4.0 or above is the industry standard for high-quality service.
• Migration: In telecom, this refers to the transfer of an existing phone system or service (e.g., traditional landlines) to a new solution, such as a Hosted PBX system.
• Music-on-Hold: The audio played to a caller while they are on hold or waiting in a Call Queue.

N

• Number Porting: The entire process of moving an existing phone number from one carrier to a new one without changing the digits. LNP governs this process.

P

• Packet Loss: Occurs when one or more voice data packets fail to reach their destination. Even small amounts of packet loss can result in missing audio, speech gaps, or “static” on the line.
• PBX (Private Branch Exchange): The internal corporate phone switch used to connect internal phones and route calls to the outside world. Modern systems use Hosted PBX or IP PBX solutions.
• PCAP (Packet Capture): A file format used to store packet data captured from a network. VoIP technicians use PCAP analysis to diagnose complex call quality issues related to Jitter, Latency, and Packet Loss.
• PoE (Power over Ethernet): A technology that allows network cables (Ethernet) to carry electrical power to the connected device alongside data. This simplifies deployment by powering VoIP Phones without the need for separate wall adapters.
• POTS (Plain Old Telephone Service): The original, traditional analog phone service delivered over copper wires, which is being phased out globally.
• PSTN (Public Switched Telephone Network): The global network of traditional, circuit-switched telephone lines and infrastructure. VoIP systems connect to the PSTN via SIP Trunks.

Q

• QoS (Quality of Service): A set of technologies used in a network to manage and prioritize specific data types, ensuring that real-time voice traffic is treated as VIP data to maintain high call quality, even during peak network congestion.
• Queue (Call Queue): A feature that holds incoming calls when agents or lines are busy, playing Music-on-Hold or informative announcements until an agent becomes available, preventing a busy signal.

R

• Ringback: The audible ringing tone that a calling party hears while they wait for the called party to answer.
• Router: A network device that directs data traffic (packets) between different networks (e.g., between your local office LAN and the public Internet).
• RTP (Real-time Transport Protocol): The primary protocol that carries the actual voice media data packets during an established VoIP call. This is distinct from the SIP signaling protocol.

S

• SBC (Session Border Controller): A specialized network device that sits at the edge of the network to secure, manage, and regulate the flow of VoIP traffic. It acts as an intelligent firewall for SIP traffic.
• SDP (Session Description Protocol): A text-based protocol that sits within the SIP messages to describe the parameters of a media session, such as which Codec should be used and the endpoints’ capabilities.
• SIP (Session Initiation Protocol): The open-standard signaling protocol responsible for establishing, modifying, and terminating real-time multimedia sessions, including VoIP calls.
• SIP Trunk: A virtual link that connects your organization’s phone system (PBX) to the outside public network (PSTN) via the Internet, replacing traditional analog or digital phone lines.
• Softphone (Soft Client): A software application used on a computer, tablet, or mobile device that replicates a phone interface, allowing users to make and receive calls without a physical desk phone.
• Soft Switch: The software equivalent of a physical telephone switchboard, used by modern carriers and service providers to manage phone call connections and traffic routing at the core of the network.
• SRTP (Secure Real-time Transport Protocol): An encrypted version of RTP used to secure voice traffic, preventing eavesdropping and ensuring confidentiality.

T/U/V/W

• TCP (Transmission Control Protocol): A foundational network protocol that ensures data delivery is reliable, meaning packets are re-sent if lost and are delivered in the correct order. It’s often used for SIP signaling.
• UDP (User Datagram Protocol): A lighter, faster network protocol used for media delivery (RTP). Unlike TCP, it does not guarantee delivery, prioritizing speed over reliability to keep real-time audio flowing with minimal Latency.
• Unified Communications (UC): The integration of various communication methods (voice, video, email, instant messaging, presence, conferencing) into a single, seamless user experience, typically managed via a single platform.
• Virtual Number: A telephone number that is not tied to a physical line or location but is instead routed digitally over the Internet to any designated destination.
• VoIP (Voice over Internet Protocol): The fundamental technology that enables voice and multimedia communication to be transmitted over IP data networks (the Internet).
• VPN (Virtual Private Network): A secure, encrypted connection across a public network (like the Internet), often used by remote employees to securely access their corporate Hosted PBX system.
• WAN (Wide Area Network): A network that spans a large geographic area, such as multiple branch offices or the connection between a local office and the public Internet.

Become an Expert, Not Just a Customer

Understanding this VoIP Terminology will fundamentally change how you interact with your phone system and service provider. It allows you to move beyond basic call features and optimize for critical business needs, such as network redundancy, quality control (monitoring MOS and mitigating Jitter), and Advanced Call Center Features.

At Seed Telecom, we are committed to providing not just a service, but a partnership built on clarity. We speak the language of VoIP, so you don’t have to worry about the technical details—just the results.

Ready to partner with experts who prioritize quality and transparency?

Reach us today:

• Web: https://seedtelecom.org/contact/
• WhatsApp: +254 723 620 620
• Email: info@seedtelecom.org