Call Service Development

Scenario Description

You can implement the call service in either of the following ways:

• For a system application, use the dialCall API to make a voice or video call. The call will be displayed on the application page.
• For a third-party application, use the makeCall API to start the system call application. Users can then make calls as needed.

Basic Concepts

• Call status code A code used to report the current call status to the application, so that the application can then take appropriate logic processing. For example, if there is no ongoing call, the application allows you to make a new call.

Constraints

1. The call service is available only on standard-system devices.
2. An available SIM card must be present on the device.

Available APIs

NOTE To maximize the application running efficiency, most API calls are called asynchronously in callback or promise mode. The following code examples use the callback mode. For details about the APIs, see call API Reference.

The observer module provides the functions of subscribing to and unsubscribing from the call service status. For details about the APIs, see observer API Reference.

How to Develop

Making a Call by Using the dialCall API (Only for System Applications)

1. Declare the required permission: ohos.permission.PLACE_CALL. This permission is of the system_basic level. Before applying for the permission, ensure that the basic principles for permission management are met. Then, declare the corresponding permission by following instructions in Declaring Permissions in the Configuration File.
2. Import the call and observer modules.
3. Invoke the hasVoiceCapability API to check whether the device supports the voice call function.
4. Invoke the dialCall API to make a call.
5. (Optional) Register the observer for call service status changes.

    // Import the required modules.
    import call from '@ohos.telephony.call';
    import observer from '@ohos.telephony.observer';
    import { BusinessError } from '@ohos.base';
   
    // Check whether the voice call function is supported.
    let isSupport = call.hasVoiceCapability();
    if (isSupport) {
        // If the device supports the voice call function, call the following API to make a call.
        call.dialCall("13xxxx", (err: BusinessError) => {
            console.log(`callback: dial call err->${JSON.stringify(err)}`);
        })
   
        // (Optional) Register the observer for call service status changes.
        class SlotId {slotId: number = 0}
        class CallStateCallback {
            state: call.CallState = call.CallState.CALL_STATE_UNKNOWN;
            number: string = "";
        }
        let slotId: SlotId = {slotId: 0}
        observer.on("callStateChange", slotId, (data: CallStateCallback) => {
            console.log("call state change, data is:" + JSON.stringify(data));
        });
    }
   

Making a Call by Using the makeCall API

1. Import the call and observer modules.

2. Invoke the hasVoiceCapability API to check whether the device supports the voice call function.

3. Call the makeCall API to launch the dial screen and display the dialed number.

4. (Optional) Register the observer for call service status changes.

    // Import the required modules.
    import call from '@ohos.telephony.call';
    import observer from '@ohos.telephony.observer';
    import { BusinessError } from '@ohos.base';
   
    // Check whether the voice call function is supported.
    let isSupport = call.hasVoiceCapability();
    if (isSupport) {
        // If the voice call function is supported, the user will be redirected to the dial screen and the dialed number is displayed.
        call.makeCall("13xxxx", (err: BusinessError) => {
            if (!err) {
                console.log("make call success.");
            } else {
                console.log("make call fail, err is:" + JSON.stringify(err));
            }
        });
        // (Optional) Register the observer for call service status changes.
        class SlotId {slotId: number = 0}
        class CallStateCallback {
            state: call.CallState = call.CallState.CALL_STATE_UNKNOWN;
            number: string = "";
        }
        let slotId: SlotId = {slotId: 0}
        observer.on("callStateChange", slotId, (data: CallStateCallback) => {
            console.log("call state change, data is:" + JSON.stringify(data));
        });
    }