PhoneLineTransportDevice Registration failure

Question

I'm developing a Winui 3 application that uses PhoneLineTransportDevice to integrate with Bluetooth devices supporting the Hands-Free Profile. I'm experiencing an issue where device registration fails despite following all the Microsoft documentation.

The issue:

• RegisterApp() silently fails (IsRegisteredAsync() returns false) even though RequestAccessAsync() returned "Allowed"
• When trying RegisterForUser() as an alternative, I get "Not authorized to perform this action"

if (pltDevice == null)
{
	logger.Warn("pltDevice was null");
    return;
}
DeviceAccessStatus accessStatus = await pltDevice.RequestAccessAsync();
if (accessStatus == DeviceAccessStatus.Allowed)
{
	pltDevice.RegisterApp();
	var isRegistered = pltDevice.IsRegistered();
	if (!isRegistered)
    {
    	logger.Warn($"Failed to register {currentDevice.Name}");
        return;
    }
    var isConnected = await pltDevice.ConnectAsync();
    if (!isConnected)
    {
    	logger.Warn($"Failed to connect to {currentDevice.Name}");
        return;
    }
}
else
{
	logger.Error($"Failed to register {currentDevice.Name}.Access Denied: {accessStatus}");
}

<rescap:Capability Name="phoneLineTransportManagement" />

The required capability was also mentioned in the manifest, and I've verified that the device supports HFP and is appropriately paired (I've paired both through the app and the OS, and both resulted in the same error).

Windows Version: 24H2 (Build 26100.3624)

Any help understanding why the registration fails would be greatly appreciated!

Answer 1

Hello,

Welcome to Microsoft Q&A!

I'm sorry to say that currently, we could offer limited help about such questions that related to the phone line.For your scenario, I suggest that you might need to open a support ticket for this. Please contact our paid support at MS Support. You will get 1:1 support on that. Select Developer Tools -> Windows UWP Development -> Windows SDK -> Windows App SDK-> other in the support page and you could contact the team. Please kindly note that your support ticket will be free if it is Microsoft's issue.

Thank you.

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