In WPF PhoneLineTransportdevice.RequestAccessAsync() always throw denied by system.

Question

In WPF PhoneLineTransportdevice.RequestAccessAsync() always throw denied by system.

鹤余 5

I want to create an App like to myphone on WPF.So I referenced winui3 in the wpf project to use Windows.ApplicationModel.Calls.But when I use PhoneLineTransportdevice.RequestAccessAsync() ,it throw denied by system and I can't register the app.

Hui Liu-MSFT 48,711 Reputation points Microsoft External Staff

2023-08-04T08:20:42.38+00:00

Hi,@鹤余. Could you show me the minimal, complete code that can reproduce your problem to analyze?

鹤余 5

This is my code. The phoneLineTransportDevice.RegisterApp() has no return,And the accessStatus is denied by system.Can't I register App in wpf ?

 PhoneLineTransportDevice? phoneLineTransportDevice = await PhoneLineTransportHelper.GetPhoneLineTransportFromBluetoothDevice(CurrentDevice);             if (!phoneLineTransportDevice.IsRegistered())             
{                 phoneLineTransportDevice.RegisterApp();             }             if (phoneLineTransportDevice != null)             
{                 
DeviceAccessStatus accessStatus = await phoneLineTransportDevice.RequestAccessAsync();                 
if (accessStatus == DeviceAccessStatus.Allowed)                 
{                     
CallService = new DeviceCallServiceProvider(CurrentDevice,phoneLineTransportDevice);                 }             
}

Hui Liu-MSFT 48,711 Reputation points Microsoft External Staff

2023-08-07T02:25:13.47+00:00

Hi,@鹤余. The PhoneLineTransportDevice.RequestAccessAsync() method requires the necessary permissions to access phone line information and make calls, and it's expected that the system might deny access if the required permissions are not granted.

In your case, you are trying to use a UWP API (PhoneLineTransportDevice) in a WPF application. While UWP APIs can be used in WPF applications through the Desktop Bridge, there might be limitations and permission issues when dealing with certain functionality that interacts with the system, like accessing phone lines.

Here are a few things you could try:

Run as Administrator: Sometimes, certain UWP APIs require administrative privileges to access specific hardware or system resources. Try running your WPF application as an administrator and see if that helps.

Check the App Manifest: Ensure that your application's manifest is properly configured to request the necessary capabilities. In a WPF project that uses UWP APIs through the Desktop Bridge, you should have a Package.appxmanifest file. Open the manifest and ensure that the required capabilities (such as cellularDeviceControl, internetClient, etc.) are declared.

Compatibility: Confirm if the specific API (PhoneLineTransportDevice.RequestAccessAsync()) is compatible with WPF applications. While WinUI is designed to be more cross-platform, not all APIs from UWP can be seamlessly integrated into WPF applications.

Debugging: Use the Debugging tools provided by Visual Studio to gather more information about the issue. You can set breakpoints and inspect variables to understand why the access request is being denied.

Error Messages: If you're receiving error messages or logs along with the "DeniedBySystem" status, they might provide more specific information about the problem. Review any error messages and try to address the root cause.

Atthaphong Thippinthong 0

@Hui Liu-MSFT I'm writing a Windows Form application following this github project https://github.com/BestOwl/MyPhone. I facing a similar problem with this thread that TransportDevice.ConnectAsync() returns 'false' always.

Here are my codes:

protected override async Task<bool> ConnectToServiceAsync()
{
    var accessResult = await TransportDevice.RequestAccessAsync();
    if (accessResult == Windows.Devices.Enumeration.DeviceAccessStatus.Allowed)
    {
        //_logger.LogInformation("PhoneLineTransportDevice access granted");
    }
    else
    {
        //_logger.LogWarning("PhoneLineTransportDevice access denied, reason: {Reason}, contine anyway", accessResult);
    }

    if (!TransportDevice.IsRegistered())
    {
        //_logger.LogInformation("PhoneLineTransportDevice not registered, registering.");
        TransportDevice.RegisterApp();
    }
    //_logger.LogInformation("PhoneLineTransportDevice registered.");

    bool success = await TransportDevice.ConnectAsync();
    if (success)
    {
        //_logger.LogInformation("CallService connected.");
        //_logger.LogInformation("Initiate PhoneLine auto discovery.");
        _taskInitPhoneLine = InitPhoneLine();
    }
    else
    {
        //_taskInitPhoneLine = InitPhoneLine();
    }
    return success;
}

Could you please help to clarify what is wrong with this?