# startSpeedTest method Null safety

Future<void> startSpeedTest(

1. int sdkAppId,
2. String userId,
3. String userSig

)

Start network speed testing, which should be avoided during video calls to ensure call quality

The speed test result will be used to optimize the SDK's subsequent selection policy. We recommend you perform the speed test before users place the first call, which will help select the optimal server. If the test result is not satisfactory, you can use a noticeable UI prompt to remind the user to select a better network. The test result is called back through `TRTCCloudListener.onSpeedTest`.

Note: the speed test will incur small basic service fees. For more information, please see Basic Services.

Parameters:

sdkAppId Application ID

userId User ID

userSig User signature

## Implementation

    Future<void> startSpeedTest(
        int sdkAppId, // Application ID
        String userId, // User ID
        String userSig // User signature
        ) {
      return _channel.invokeMethod('startSpeedTest', {
        "sdkAppId": sdkAppId,
        "userId": userId,
        "userSig": userSig,
      });
    }