📖 VoIP glossary

Telco jargon, translated.

Every TLA the industry will throw at you — explained the way your mate down the pub would explain it.

Busy Lamp Field. The little light on a desk phone next to a colleague’s name that turns red when they’re on a call.

Calling Line Identifier — the number that shows up on someone’s phone when you ring them.

Wireless protocol used by cordless desk phones and headsets. Better range than Bluetooth, dedicated voice spectrum.

Direct Inward Dial — a published phone number that rings to a specific destination inside your system.

Microsoft Teams feature that lets a third-party carrier (like us) provide PSTN calling, instead of buying Microsoft Calling Plans.

International number format, e.g. +611300250319. The standard format we expect for portability.

Fax over IP — for sending faxes over a SIP connection. Mostly replaced by e-fax now.

Wideband audio codec (G.722 / Opus) — sounds noticeably clearer than old PSTN narrowband.

A group of extensions that ring in sequence (or simultaneously) until someone answers.

Interactive Voice Response — "press 1 for sales, 2 for support". Auto-attendant.

Australia’s National Broadband Network. Your internet pipe — VoIP rides on top of it.

Private Branch eXchange — the phone system that connects internal handsets to outside lines.

Power over Ethernet — desk phones powered by the network cable, no separate power brick.

Moving a phone number from one carrier to another while keeping the number.

Public Switched Telephone Network — the "real" phone network, what you call when you dial out.

Session Border Controller — the security gateway between your phone system and the public internet.

Session Initiation Protocol — the signalling layer that sets up VoIP calls.

Service Level Agreement — the uptime / response promise we make in writing.

Secure Real-time Transport Protocol — encrypted voice on the wire.

A bunch of phone-call paths between two systems (e.g. between us and your Teams tenant).

Making one number ring two devices simultaneously (e.g. desk + mobile).

Voice over IP — phone calls carried over an internet connection.