# Glossary The Sinch platform uses a handful of terms that are not obvious at first. Here's what each one means. ## Voice callback events When something happens to a call on the Sinch network, Sinch sends an HTTP callback to your Function. There are four of them, and together they describe the call's lifecycle. ### ICE — Incoming Call Event Fired when a phone call arrives at one of your Sinch phone numbers. Your function responds with [SVAML](#svaml) to decide what happens next: play a message, connect to another number, run a menu, record, bridge to SIP, etc. ICE is where most Functions do their work. ### ACE — Answered Call Event Fired when an **outbound** call you initiated is answered. Use this to start doing something once the other party picks up — play a message, start a conference, run an IVR on the callee. ### PIE — Prompt Input Event Fired when a menu interaction completes. The caller pressed a DTMF digit (or said something that was recognized), and the menu you started via SVAML returned a result. You get the result and respond with the next SVAML step. ### DICE — Disconnected Call Event Fired when the call ends. Informational only — use it for logging, billing, cleanup. ### Typical lifecycle ``` Inbound call: ICE → (optional PIE loop for menus) → DICE Outbound call: ACE → (optional PIE loop) → DICE ``` ## SVAML — Sinch Voice Application Markup Language A JSON format for controlling calls. When your Function responds to an ICE callback, you return SVAML telling Sinch what to do: "say this message", "play this audio", "connect to this number", "run this menu", and so on. Both runtimes provide fluent builders so you never write raw JSON: - **Node:** `new IceSvamlBuilder().say('Hello').connectPstn('+15551234567').build()` - **C#:** `new IceSvamletBuilder().Instructions.Say("Hello").Action.ConnectPstn("+15551234567").Build()` See the [SVAML cheat sheet](/docs/functions/reference/svaml-cheatsheet) for the most-used actions, or the [full SVAML spec on developers.sinch.com](/docs/voice/api-reference/svaml/) for every action and option. ## Voice App A configuration entity in Sinch that owns your voice functionality. A Voice App has: - An **application key + secret** (authentication) - **Callback URLs** — where Sinch sends ICE, ACE, PIE, DICE events - Assigned phone numbers that route calls to it When you deploy a Function that handles voice, the CLI can update the Voice App's callback URL to point at your Function's new URL. That linking is managed via `sinch.json` in your project. ## Conversation App The multi-channel messaging equivalent of a Voice App. A Conversation App has: - An **App ID** - **Channel credentials** (WhatsApp Business Account, Messenger page token, Viber credentials, etc.) - **Webhook URL** — where Sinch posts incoming messages and delivery events One Conversation App can handle many channels simultaneously. SMS, WhatsApp, Messenger, Viber, RCS, MMS all go through the same webhook. ## Sinch Dashboard The web-based control surface for your Sinch account, at [dashboard.sinch.com](https://dashboard.sinch.com). It's where you: - Create and manage Projects - Issue and rotate API keys - Configure Voice Apps and Conversation Apps - Buy, manage, and release phone numbers - View usage, billing, and logs The Sinch CLI is the terminal-side complement to the Dashboard — everything the CLI does goes through the same underlying APIs, so work done in either place shows up in the other. ## Project (Project ID) The top-level tenant in your Sinch account. Everything — Voice Apps, Conversation Apps, phone numbers, API credentials — belongs to a Project. Find your Project ID in the [Sinch Dashboard](https://dashboard.sinch.com) under Settings. Most CLI commands need a Project ID to know which account to operate on; `sinch auth login` stores it for you. ## FunctionContext The object your handler receives as its first parameter. It gives you cache, storage, config, logger, and pre-wired SDK clients for Voice, Conversation, SMS, and Numbers. Think of it as "the standard library of the Sinch runtime." See [context-object](/docs/functions/functions/concepts/context-object) for the full tour. ## Handler A function (Node) or controller method (C#) that Sinch invokes over HTTP. - **Voice callbacks** map to specific handler names: `ice`, `ace`, `pie`, `dice`. - **Custom HTTP endpoints** map by URL path — export a function named `status` and it's available at `POST /status`. (Node.) Or add a controller action in C#. See [handlers](/docs/functions/functions/concepts/handlers) for how the mapping works. ## Template A pre-built starting point for a Function. `sinch templates list` shows what's available; `sinch functions init