Terminology

A leg An A leg is the initial leg of a call. When someone dials your Plivo number, the inbound call connection between the caller and your Plivo number is the A leg. For more information about call legs and types of calls, refer to our Voice Overview page.
API An application programming interface is a computing interface that defines interactions between multiple software intermediaries.
api_id A Plivo api_id is a unique ID for each API request made.
B leg The B leg represents the secondary leg of a call. For example, if an inbound call to your Plivo number is forwarded to another line, the forwarded leg is the B leg. For more information about call legs and types of calls, refer to our Voice Overview page.
Carrier A telecom carrier is a company that’s authorized by regulatory agencies to operate a telecommunications system and provide mobile or landline connections to consumers and businesses.
CDR A Call Detail Record contains all the details about and serves as the source of truth for that call. You can export CDRs from Voice > Logs > Calls on the Plivo console.
Client SDK Plivo’s client software development kits contain wrapper classes that help you connect directly to the Plivo Voice Platform to make and receive calls using a Plivo endpoint or client. Plivo provides Browser and mobile (iOS and Android) client SDKs that you can integrate with your web and mobile apps to enable voice calling.
DID Direct Inward Dial numbers are virtual phone numbers that Plivo provides and on which you can receive calls. You can programmatically control calls coming in to these numbers by assigning a Plivo application to them using the Plivo console. For more information, refer to our Receive Incoming Calls guide.
DTMF Dual-tone multi-frequency tones, also called Touch-Tone, are the tones produced when someone presses a telephone keypad. DTMF tones are collected from users and passed over a communications network to a destination for processing. DTMF inputs are useful for IVR systems and use cases that involve user-directed interaction.
Hardphone A hardphone is a hardware-based IP phone from vendors such as Cisco, Polycom, Mitel, and Snom
IVR Interactive voice response systems let phone systems route calls without operator intervention. They depend on users speaking or entering keypad presses to traverse a menu of choices.
PoP A point of presence is an access point that connects communication networks. PoPs are often located near large Internet exchange points (IXP) to minimize latency and maximize available bandwidth. Plivo maintains seven PoPs strategically placed across four continents to ensure optimal voice quality.
PSTN The public switched telephone network is the circuit-switched telephone network that has been in use since the 1800s. It comprises telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all interconnected by switching centers. It’s also referred to as POTS — plain old telephone service. By contrast, VoIP uses packet switching.
Routing Routing, in telephony, is the process of selecting the priority carrier for a given destination prefix and country.
Sandbox number Sandbox numbers are number that have been verified for use with Plivo. You must use a sandbox number to make a call or send a message if you have a Plivo trial account.
SDK A software development kit is a package of prewritten code that developers can reuse to minimize the amount of unique code they need to develop themselves.
Server SDK Plivo’s server software development kits help developers quickly integrate their code with Plivo APIs in their language of choice. They contains functions and methods that can be used to trigger API requests and generate XML to manage call flows and implementations. Plivo provides server SDKs for seven languages: PHP, Python, Node.js, Java, .NET (C#), Ruby, and Go.
SIP Session Initiation Protocol is a signaling protocol for controlling and signaling multimedia communication on VoIP networks.
SIP URI A SIP URI (uniform resource identifier) is an address for a SIP-enabled device. SIP URIs are written in the format user@domain.tld.
Softphone A softphone is a software-based implementation of a SIP phone client. Examples: Zoiper, Bria, X-Lite
UUID A universally unique identifier — a 128-bit label, calculated using standard formulas in such a way that the probability of having duplicate UUIDs is negligible. Plivo uses UUIDs to identify various entities, including individual calls, messages, and API requests.
VoIP Voice over Internet Protocol, also called IP telephony, is a set of methods and technologies for the delivery of voice and multimedia communications over packet-switched IP networks such as the internet.
WebRTC Web Real-Time Communication is a World Wide Web Consortium (W3C) specification that allows audio and video communication to work inside web pages and supports browser-to-browser applications for voice calling, video chat, and P2P file sharing without the need for plugins.
XML Extensible Markup Language defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. Plivo uses XML documents to control communication flows.