# Room (SIP)

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Video SDK offers the ability to call out to conference room devices using the H.323/SIP [Conference Room Connector](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0060661). _H.323 and Session Initiation Protocol (SIP) are protocols for sending media online._

## Prerequisites

-   [Video SDK Account](https://zoom.us/pricing/developer).
-   [Conference Room Connector Plan](https://zoom.us/billing).
-   **The session must exist** - there must be at least one user in the session before you can use call in or call out.

## Check whether CRC is available

Use `isCRCEnabled()` on `ZoomVideoSDKCRCHelper` to see if CRC is available for this user.

```swift
if let crcHelper = ZoomVideoSDK.shareInstance()?.getCRCHelper() {
    let isEnabled = crcHelper.isCRCEnabled()
}
```

```objectivec
ZoomVideoSDKCRCHelper *crcHelper = [[ZoomVideoSDK shareInstance] getCRCHelper];
BOOL isEnabled = [crcHelper isCRCEnabled];
```

## Dial out

Use `callCRCDevice` on `ZoomVideoSDKCRCHelper` to call out to a Cloud Room Connector (CRC) device to join a session.

```swift
if let crcHelper = ZoomVideoSDK.shareInstance()?.getCRCHelper() {
    crcHelper.callCRCDevice("7357@test.plcm.vc", protocol: ZoomVideoSDKCRCProtocol_SIP)
}
```

```objectivec
ZoomVideoSDKCRCHelper *crcHelper = [[ZoomVideoSDK shareInstance] getCRCHelper];
[crcHelper callCRCDevice:@"7357@test.plcm.vc" protocol:ZoomVideoSDKCRCProtocol_SIP];
```

### Cancel room device call

Cancel the CRC call with `cancelCallCRCDevice` if you need to cancel the call out request before it is complete.

```swift
if let crcHelper = ZoomVideoSDK.shareInstance()?.getCRCHelper() {
    crcHelper.cancelCallCRCDevice()
}
```

```objectivec
ZoomVideoSDKCRCHelper *crcHelper = [[ZoomVideoSDK shareInstance] getCRCHelper];
[crcHelper cancelCallCRCDevice];
```

### Callback for call status

Listen for CRC device call state changes with the `onCallCRCDeviceStatusChanged` callback under `ZoomVideoSDKDelegate`. States include `ZoomVideoSDKCRCCallStatus_Busy`, `ZoomVideoSDKCRCCallStatus_Decline`, `ZoomVideoSDKCRCCallStatus_Failed`, `ZoomVideoSDKCRCCallStatus_Ring`, `ZoomVideoSDKCRCCallStatus_Success`, and `ZoomVideoSDKCRCCallStatus_Timeout`.

```swift
func onCallCRCDeviceStatusChanged(_ state: ZoomVideoSDKCRCCallStatus) {
    print("CRC call status: \(state)")
}
```

```objectivec
- (void)onCallCRCDeviceStatusChanged:(ZoomVideoSDKCRCCallStatus)state {
    NSLog(@"CRC call status: %lu", (unsigned long)state);
}
```

### Webhooks

Use the following webhooks to get notified of the call out status.

-   [`session.user_room_system_callout_accepted`](/docs/api/video-sdk/events/#tag/session/POSTsession.user_phone_callout_accepted)
-   [`session.user_room_system_callout_failed`](/docs/api/video-sdk/events/#tag/session/POSTsession.user_room_system_callout_failed)
-   [`session.user_room_system_callout_missed`](/docs/api/video-sdk/events/#tag/session/POSTsession.user_phone_callout_missed)
-   [`session.user_room_system_callout_rejected`](/docs/api/video-sdk/events/#tag/session/POSTsession.user_phone_callout_rejected)
-   [`session.user_room_system_callout_ringing`](/docs/api/video-sdk/events/#tag/session/POSTsession.user_room_system_callout_ringing)

## Dial-in

To dial in to a Video SDK session, append the session number to `@zoomcrc.com`, for example `{SESSION_NUMBER}.{PASSCODE}@zoomcrc.com`, and provide the passcode when prompted. You can obtain these values using an SDK function or API endpoints.

### Reserve a session to set up dial-in access

To enable dial-in, you must reserve a session ID in advance using the [Create a session API](/docs/api/video-sdk/#tag/sessions/post/videosdk/sessions). This reserves the session for up to 24 hours for your specified session name. When you start and join the session with that session name during the reservation period, dial-in users will be able to access it.

### Get dial-in information

Get dial-in details using either the SDK function or API endpoints.

#### Using an SDK function

To retrieve dial-in information with the `getSessionSIPAddress` function, the returned value will be in this format:
`{SESSION_NUMBER}.{PASSCODE}@global.zoomcrc.com`

For example:

```swift
if let crcHelper = ZoomVideoSDK.shareInstance()?.getCRCHelper() {
    let sipAddress = crcHelper.getSessionSIPAddress()
}
```

```objectivec
ZoomVideoSDKCRCHelper *crcHelper = [[ZoomVideoSDK shareInstance] getCRCHelper];
NSString *sipAddress = [crcHelper getSessionSIPAddress];
```

#### Using API endpoints

Get dial-in information using either the [Create a session](/docs/api/video-sdk/#tag/sessions/post/videosdk/sessions) or [Get session details](/docs/api/video-sdk/#tag/sessions/get/videosdk/sessions/{sessionId}) APIs.

**Sample request**

```javascript
var sipDialInAddress = responseBody.session_number + "@zoomcrc.com";
var sipDialInPasscode = responseBody.session_password;
```

**Sample response**

```json
{
    "session_id": "sfk/aOFJSJSYhGwk1hnxgw==",
    "session_number": 97763643886,
    "session_name": "My session",
    "session_password": "123456",
    "passcode": "123456",
    "created_at": "2022-03-25T07:29:29Z",
    "settings": {
        "auto_recording": "cloud",
        "global_dial_in_countries": [
            //...
        ],
        "global_dial_in_numbers": [
            //...
        ]
    }
}
```

## Custom welcome message

You can customize the welcome message that H.323/SIP participants hear when they join a session. See [H.323/SIP Conferencing](/docs/build/account/#h323sip-conferencing) in the account settings documentation for details.

## More SIP features

For the full set of SIP features, see [ZoomVideoSDKCRCHelper in the Video SDK Reference](https://marketplacefront.zoom.us/sdk/custom/ios/interface_zoom_video_s_d_k_c_r_c_helper.html).