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# Constants

> Relay constants for call states, connect states, event types, and message states.

[connectevent-connectstate]: /docs/server-sdks/reference/typescript/relay/events

[call-on]: /docs/server-sdks/reference/typescript/relay/call

[relayevent-eventtype]: /docs/server-sdks/reference/typescript/relay/events

The `@signalwire/sdk` package re-exports string constants for call states,
connect states, event types, and message states. Import any of them from the
package root:

```typescript {2-7}
import {
  CALL_STATE_ANSWERED,
  CALL_STATE_ENDED,
  CONNECT_STATE_CONNECTED,
  EVENT_CALL_STATE,
  MESSAGE_STATE_DELIVERED,
} from '@signalwire/sdk';
```

## Call States

Constants representing the lifecycle states of a Relay call. A call progresses
through these states in order: `created` -> `ringing` -> `answered` -> `ending` -> `ended`.

| Constant              | Value        | Description                        |
| --------------------- | ------------ | ---------------------------------- |
| `CALL_STATE_CREATED`  | `"created"`  | Call object has been created       |
| `CALL_STATE_RINGING`  | `"ringing"`  | Call is ringing at the destination |
| `CALL_STATE_ANSWERED` | `"answered"` | Call has been answered             |
| `CALL_STATE_ENDING`   | `"ending"`   | Call is in the process of ending   |
| `CALL_STATE_ENDED`    | `"ended"`    | Call has ended                     |

---

## Connect States

Constants representing the state of a call bridge (connect) operation. Used in
[`ConnectEvent.connectState`][connectevent-connectstate].

| Constant                     | Value            | Description                  |
| ---------------------------- | ---------------- | ---------------------------- |
| `CONNECT_STATE_CONNECTING`   | `"connecting"`   | Bridge is being established  |
| `CONNECT_STATE_CONNECTED`    | `"connected"`    | Bridge is active             |
| `CONNECT_STATE_DISCONNECTED` | `"disconnected"` | Bridge has been disconnected |
| `CONNECT_STATE_FAILED`       | `"failed"`       | Bridge attempt failed        |

---

## Event Types

String constants for Relay event types. Use these when registering event
handlers with [`Call.on()`][call-on] or when matching against
[`RelayEvent.eventType`][relayevent-eventtype].

### Calling Events

| Constant                 | Value                        |
| ------------------------ | ---------------------------- |
| `EVENT_CALL_STATE`       | `"calling.call.state"`       |
| `EVENT_CALL_RECEIVE`     | `"calling.call.receive"`     |
| `EVENT_CALL_CONNECT`     | `"calling.call.connect"`     |
| `EVENT_CALL_PLAY`        | `"calling.call.play"`        |
| `EVENT_CALL_COLLECT`     | `"calling.call.collect"`     |
| `EVENT_CALL_RECORD`      | `"calling.call.record"`      |
| `EVENT_CALL_DETECT`      | `"calling.call.detect"`      |
| `EVENT_CALL_FAX`         | `"calling.call.fax"`         |
| `EVENT_CALL_TAP`         | `"calling.call.tap"`         |
| `EVENT_CALL_SEND_DIGITS` | `"calling.call.send_digits"` |
| `EVENT_CALL_DIAL`        | `"calling.call.dial"`        |
| `EVENT_CALL_REFER`       | `"calling.call.refer"`       |
| `EVENT_CALL_DENOISE`     | `"calling.call.denoise"`     |
| `EVENT_CALL_PAY`         | `"calling.call.pay"`         |
| `EVENT_CALL_QUEUE`       | `"calling.call.queue"`       |
| `EVENT_CALL_STREAM`      | `"calling.call.stream"`      |
| `EVENT_CALL_ECHO`        | `"calling.call.echo"`        |
| `EVENT_CALL_TRANSCRIBE`  | `"calling.call.transcribe"`  |
| `EVENT_CALL_HOLD`        | `"calling.call.hold"`        |
| `EVENT_CONFERENCE`       | `"calling.conference"`       |
| `EVENT_CALLING_ERROR`    | `"calling.error"`            |

### Messaging Events

| Constant                  | Value                 |
| ------------------------- | --------------------- |
| `EVENT_MESSAGING_RECEIVE` | `"messaging.receive"` |
| `EVENT_MESSAGING_STATE`   | `"messaging.state"`   |

---

## Message States

Constants representing the lifecycle states of an SMS/MMS message. Outbound
messages progress through: `queued` -> `initiated` -> `sent` -> `delivered`
(or `undelivered` / `failed`). Inbound messages arrive with state `received`.

| Constant                    | Value           | Description                            |
| --------------------------- | --------------- | -------------------------------------- |
| `MESSAGE_STATE_QUEUED`      | `"queued"`      | Message has been queued for sending    |
| `MESSAGE_STATE_INITIATED`   | `"initiated"`   | Send process has started               |
| `MESSAGE_STATE_SENT`        | `"sent"`        | Message has been sent to the carrier   |
| `MESSAGE_STATE_DELIVERED`   | `"delivered"`   | Message was delivered to the recipient |
| `MESSAGE_STATE_UNDELIVERED` | `"undelivered"` | Message could not be delivered         |
| `MESSAGE_STATE_FAILED`      | `"failed"`      | Message send failed                    |
| `MESSAGE_STATE_RECEIVED`    | `"received"`    | Inbound message received               |

## Typed state unions

Each state family also has a string-literal union type, the list of its terminal
values, and a predicate, so you can narrow states without comparing against
individual constants.

| Type                                          | Terminal values                                                     | Predicate                       |
| --------------------------------------------- | ------------------------------------------------------------------- | ------------------------------- |
| `CallState`                                   | `CALL_STATE_TERMINAL` = `["ended"]`                                 | `isCallStateTerminal(state)`    |
| `DialState` (`dialing`, `answered`, `failed`) | `DIAL_STATE_TERMINAL` = `["answered", "failed"]`                    | `isDialStateTerminal(state)`    |
| `MessageState`                                | `MESSAGE_STATE_TERMINAL` = `["delivered", "undelivered", "failed"]` | `isMessageStateTerminal(state)` |

Two more closed sets are exported for method options: `TtsGender` (`"male"` or
`"female"`) and `FaxTone` (`"CED"` or `"CNG"`).

```typescript {1,4}
import { isMessageStateTerminal, type MessageState } from '@signalwire/sdk';

function handleMessageState(message: { state: MessageState }) {
  if (isMessageStateTerminal(message.state)) {
    console.log('Message delivery complete');
  }
}
```

## **Example**

```typescript {11,20}
import {
  CALL_STATE_ANSWERED,
  CALL_STATE_ENDED,
  EVENT_CALL_STATE,
  isMessageStateTerminal,
} from '@signalwire/sdk';
import type { CallStateEvent } from '@signalwire/sdk';

// Use in event handlers
function handleCallState(event: CallStateEvent) {
  if (event.callState === CALL_STATE_ANSWERED) {
    console.log('Call answered!');
  } else if (event.callState === CALL_STATE_ENDED) {
    console.log(`Call ended: ${event.endReason}`);
  }
}

// Check terminal message states
function handleMessageState(message: { state: string }) {
  if (isMessageStateTerminal(message.state)) {
    console.log('Message delivery complete');
  }
}
```

> Relay constants for call states, connect states, event types, and message states.