# Browser Calling Glossary: WebRTC, TURN, SLA | CallCeptor

> Plain definitions of the terms used in website calling: click-to-call, WebRTC, DTLS-SRTP, TURN relay, page-based routing, callback SLA, legal hold and more.

Source: https://callceptor.com/glossary/

Glossary

## Website calling terms, in plain words

The words that come up when a financial firm puts a Call button on its website, from the browser standard underneath to the compliance settings on top.

### 1600-series numbers

Phone numbers starting with 1600 that the Indian telecom regulator set aside for service and transactional calls from regulated financial entities, so customers can recognise genuine calls from banks, brokers and fund houses.

### Browser calling

A voice call made from a web browser using the microphone and speakers of the device, with no phone line and no app on the caller's side. Also called browser-to-browser calling or website calling. [What is browser calling?](https://callceptor.com/guides/what-is-browser-calling/)

### Callback SLA

The time a team commits to calling back a visitor whose call was missed, such as two working hours. A callback queue shows the time left and escalates overdue callbacks. [Callbacks](https://callceptor.com/features/callbacks/)

### Click-to-call

A button on a website that starts a voice call with the business when the visitor clicks it. In browser click-to-call the call runs inside the browser; in older callback-style click-to-call the visitor types their number and the business phones them. [Browser calling](https://callceptor.com/features/browser-calling/)

### Disposition

The outcome an agent records at the end of a call, such as account opening started, query resolved or call back later.

### DPDP Act

India's Digital Personal Data Protection Act, 2023, which sets rules for collecting and processing personal data, including consent and the rights of the people the data is about. [Privacy policy](https://callceptor.com/privacy/)

### DTLS-SRTP

The encryption WebRTC uses for call audio. DTLS exchanges the keys and SRTP encrypts each audio packet, so the media is encrypted in transit by default. [Security](https://callceptor.com/security/)

### IVR

Interactive voice response: the phone menu that asks callers to press a number to reach a department.

### Legal hold

A flag on a call or a client that stops recordings and records from being deleted at the end of their retention period, usually because of a dispute or investigation. [Recording](https://callceptor.com/features/recording/)

### Longest idle

A ring strategy that offers each new call to the agent who has been without a call for the longest time.

### Mobile fallback

Ringing an agent's mobile over the phone network when they don't answer in the browser, so a website call still reaches a person. [Mobile fallback](https://callceptor.com/features/mobile-fallback/)

### Opus

The audio codec WebRTC uses for voice. It carries a wider range of the voice than a standard phone line and copes well with packet loss on mobile networks.

### Page-based routing

Sending a website call to a department based on the URL the visitor called from, instead of asking them to choose from an IVR menu. [Routing website calls by page](https://callceptor.com/guides/route-website-calls-by-page/)

### PSTN

The public switched telephone network: ordinary landline and mobile calls. CallCeptor uses it only when a call rings an agent's mobile or when an agent calls a visitor back.

### Round robin

A ring strategy that offers each new call to the next agent in turn, spreading calls evenly across a team.

### TURN relay

A server that forwards call audio when two devices can't connect directly, for example behind an office or bank firewall. Running TURN over TLS on port 443 lets calls through networks that only allow web traffic.

### UTM tags

Parameters added to a link, such as utm_source and utm_campaign, that tell analytics tools which campaign brought a visitor. CallCeptor stores them on each call lead. [Lead inbox](https://callceptor.com/features/lead-inbox/)

### Warm transfer

Passing a call to a colleague after speaking to them first. In a blind transfer, the call is passed on without that introduction.

### WebRTC

Web Real-Time Communication, an open standard from the W3C and IETF that lets browsers send audio, video and data to each other directly. Chrome, Edge, Firefox and Safari all support it.

### Questions we get asked

#### What is the difference between click-to-call and browser calling?

Click-to-call is any button or link that starts a call. Browser calling is a kind of click-to-call where the call itself runs inside the web browser over WebRTC, so the visitor needs no phone and no app.

#### Is a WebRTC call encrypted?

Yes. WebRTC requires every audio stream to be encrypted with DTLS-SRTP, so the call cannot be listened to on the network between the visitor's browser and the agent.

#### What does a TURN server do in a browser call?

A TURN server relays the call audio when a firewall or office network blocks a direct connection between the two browsers. Without one, some calls from corporate networks would fail to connect.