Common VoIP Acronyms, SIP Acronyms and What They Mean

UCaaS, BYOD, PSTN—what do all these letters stand for? Here's a handy guide to the most common VoIP acronyms. We aim to cut through the confusion with concise definitions.

VoIP Acronyms and SIP Acronyms

ACD: Automatic Call Distribution

Automatic call distribution is technology that routes incoming phone calls within an organization. For example, ACD can be set up so calls are delivered to contact center agents in a specific order based on their experience level. Another possibility is to ring all phones in a department at the same time so the first available person can pick up.

ATA: Analog Telephone Adapter

This piece of equipment connects traditional analog business phones—those with RJ11 jacks—to the internet so you can use them with a VoIP phone system. While this option may reduce your upfront costs, keep in mind that ATAs may negate some VoIP business features, like HD voice.

BYOD: Bring Your Own Device

Some VoIP services operate under a Bring Your Own Device (BYOD) policy where the customers are responsible for purchasing IP phones that best suit their businesses. This is in contrast to services that require customers to purchase specific phone models or phones sold directly from the service provider itself. This term also refers to when employees are allowed to use their personal devices, such as mobile phones, to access corporate information and apps for communication and collaboration purposes.

Proponents of BYOD say it gives customers more leeway in purchasing the phones that are right for their respective businesses.

CNAM: Caller ID Name

To populate their Caller IDs for incoming and outgoing phone calls, phone service providers pull information from a database that’s called a CNAM, which is short for Calling Name. There isn’t one centralized CNAM source, so service providers can choose from many different CNAMs. Each one maintains its private database of phone number/name pairs in the U.S. and abroad.

CTI: Computer Telephony Integration

This term refers to any technology that makes it possible to coordinate interactions on a telephone and a computer. CTI usually refers to apps that help users access their phone features from their desktops or mobile devices. CTI can also describe server-based functionality, such as automatic call routing.

DID: Direct Inward Dialing

Direct Inward Dialing (DID) is when a service provider blocks off a range of numbers associated with one main number. This allows you to assign unique numbers (a.k.a. extensions) to all the employees on the phone system without having to route new physical lines in the office.

The DID for (555)-234-5632 allows you to own that number, along with any number that comes after 5632. For instance, DID numbers for the prior number include:

(555)-234-5632-3432
(555)-234-5632-4350
(555)-234-5632-XXXX

All of these numbers are protected under DID.

DTMF: Dual-Tone Multi-Frequency

Dual-Tone Multi-Frequency (DTMF), sometimes called "Touch Tone" dialing, refers to the popular keypad and dial tones that replaced rotary dialing some years ago. Almost all U.S. phones, including VoIP phones, use the DTMF keypad and dial tones.

E911: Enhanced 911

E911, also known as internet-only 911 dialing, is part of the Federal Communications Commission’s system of regulations to help ensure that when a caller dials 911, their location and callback phone number are relayed to emergency dispatchers. The address that an E911 service customer registers with their VoIP provider is simultaneously sent with their phone number to the emergency center assigned to that location. It is vital that VoIP customers update their address if they move so first responders can be sent to the new location.

FMC: Fixed Mobile Convergence

Fixed Mobile Convergence is a technology solution that removes the barriers between wireless and wired telecommunication networks. A good example of FMC is the ability to seamlessly access and use your office phone line from apps on your smartphone or computer.

IP: Internet Protocol

Internet protocol is the set of rules for formatting digital packets of information so communications can be sent and received by other computers on an internet network.

ITSP: Internet Telephony Service Provider

An Internet Telephony Service Provider (ITSP) is a company that provides internet telecommunications services based on VoIP. This is just another name for a VoIP service provider.

IVR: Interactive Voice Response

IVR refers to technology that allows users to interact with computers by either speaking commands or entering information on a keypad. In the telecom industry, IVR is often used so callers can navigate a company’s telephone network to reach contact centers, departments, individual employees and more through keypad presses or speech recognition.

LAN: Local Area Network

A Local Area Network (LAN) connects computers within a set area, such as an office, a house or a school. Your IP phones will either connect wirelessly or directly plug into your LAN through wall jacks, routers, and other ports to access your VoIP service. The LAN must have an active internet connection for your VoIP phones to make and take calls.

However, not all VoIP phones need to be connected to your office's LAN to make and receive calls. Remote workers can set up desk phones, softphones, or web phones at offsite locations yet still remain connected to the office phone network through an internet connection. This also means that you can keep the same extension number no matter where you are in the U.S.

LEC: Local Exchange Carrier

Local exchange carrier is a regulatory telecommunications term for the wireline phone company responsible for delivering calls within a regional area. Sometimes LECs are classified as either incumbent (ILEC) or competitive (CLEC) because the original LECs have different regulations from the newer phone service providers. For example, AT&T is an ILEC because it owns its local Public Switched Telephone Network and OnSIP is a CLEC because it is newer and contracts with other CLECs across the country to provide inbound and outbound calling for their customers.

LNP: Local Number Portability

Local Number Portability (LNP), also known as number porting or number transferring, allows you to keep your current phone number when you switch from one telephone service provider to another.

PBX: Private Branch Exchange

Private Branch Exchange (PBX) refers to a business phone system that manages all incoming and outgoing calls, as well as calls between internal extensions. There are several different kinds of PBXs:

Analog PBX: Built on copper wire (see: PSTN/POTS), analog PBXs are business phone systems with fairly basic features and landline calling technology. Phone system hardware is kept at the site of your business.
IP PBX
- On-premise PBX: Powered by VoIP, on-premise PBXs keep phone system hardware at the site of your business. Your IT staff is in charge of maintenance, and it’s run by specialized programs such as Asterisk.
- Hosted PBX: Built with VoIP technology, hosted PBX systems use hardware that is stored offsite, under maintenance of the service provider. These systems offer businesses a wide range of features, including third-party integrations with Customer Relationship Management (CRM) platforms.

POTS: Plain Old Telephone Service

POTS is telecom shorthand for Plain Old Telephone Service, the original or traditional phone service that began in the late 1880s, as opposed to internet-based VoIP phone service. POTS requires copper wire links, while OnSIP phone service is almost entirely delivered via the internet—or “in the cloud.”

PSTN: Public Switched Telephone Network

The Public Switched Telephone Network (PSTN) is a series of networks that includes telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables. This interconnected series of networks allows different kinds of phones, such as landline and mobile devices, to communicate with each other. The PSTN is sometimes inaccurately referred to as the Plain Old Telephone Service (POTS).

QoS: Quality of Service

Quality of Service (QoS) measures the performance and quality of a VoIP network. Bad QoS can lead to dropped or distorted calls. QoS is normally rated from the perspective of the user.

SaaS: Software as a Service

SaaS is a method of delivering computer applications that are centrally hosted, usually on the internet. Users purchase a pay-as-you-go subscription to access the applications and associated data through an internet web browser. This model makes it easy for businesses to quickly and affordably provide employees with communication tools.

SIP: Session Initiation Protocol

Session Initiation Protocol (SIP) is a set of rules that govern the formatting of data sent over the internet. SIP formatting allows packets of telephony data to be routed cheaply and efficiently between private and local phone systems. Originally developed for voice calls, SIP is now used for instant messaging, video conferencing and the transferring of media files. SIP (one of the most important SIP acronyms) is the primary engine of many VoIP phone systems.

SLA: Service Level Agreement

An SLA is a contract between a service provider and a customer that generally includes details about the scope and duration of the service and its delivery, metrics on how the service is measured, the responsibilities of both parties, and ways to report any problems. Internet service providers often have SLAs where customers can find bandwidth details and information about what they can do if their service isn’t meeting their expectations.

UC or UCaaS: Unified Communications or Unified Communications as a Service

Unified Communications (UC) or Unified Communications as a Service (UCaaS) refers to the integration of various communications services such as voice, video, chat, email, and voicemail under a single user interface.

VoIP: Voice over Internet Protocol

Voice over Internet Protocol (VoIP) is technology that delivers voice communications, streaming video, and other media over the internet. VoIP is also shorthand for a wide variety of phone services, including hosted PBX, on-premise PBX, and SIP trunking.

Business VoIP refers to a class of professional phone systems that can make and take business-quality phone calls via the internet. Business VoIP phone systems typically offer features such as voicemail, call transfer, call conferencing, and many others.

A hosted VoIP phone system keeps its hardware offsite, under the maintenance of the service provider. An on-premise VoIP phone system, on the other hand, keeps its hardware onsite, at the business itself. (See: hosted PBX, on-premise PBX.)

WAN: Wide Area Network

WAN refers to telecommunication networks that cover a large area, linking across regional or national boundaries. It is most effective for business and government entities that communicate with employees and customers from various locations.

XMPP: Extensible Messaging and Presence Protocol

“Messaging” is the most important term to remember in this acronym. XMPP is OnSIP’s way of Instant Messaging, which customers are able to access when signing up for one of our services.

Don’t Let All These Letters Scare You Off

Even if you don't plan to switch to a VoIP phone system, the information here can help you make better decisions about your company's communications needs. Here are some additional links to help you in your research: