Self-Managed ConnectionService Not Working

HI

We are currently building a VOIP calling application with a particular focus on your brand of tablets. However, we are experiencing some issues with the calling support.

In total we have 4 Samsung tablets; SM-T395, SM-T390, SM-T590, and the SM-T290. Of these, we are only having issues with the SM-T290.

We have implemented a self-managed connection service as documented by google at -
https://developer.android.com/guide/topics/connectivity/telecom/selfManaged

On the SM-T290 incoming connections work correctly, but when attempting to place an outgoing call using TelecomManager.placeCall(…), neither of the expected methods on my service are called.

onCreateOutgoingConnection(…) or onCreateOutgoingConnectionFailed(…)

Looking through an unfiltered logcat when using placeCall(…) We see the following on the devices.

SM-T395 (Working)
I/Telecom:SamsumgTelecomSystemManager: isVoiceCapable(internal) : true

SM-T390 (Working)
I/Telecom:SamsumgTelecomSystemManager: isVoiceCapable(internal) : false
I/Telecom:SamsumgCmcSystemListener: isVoiceCapable - isSdDevice : true

SM-T290 (Not Working)
I/Telecom:SamsumgTelecomSystemManager: isVoiceCapable(internal) : false
I/Telecom:SamsumgCmcSystemListener: isVoiceCapable - isSdDevice : false

On the working devices, there is more log output from calling classes that I have omitted. But on the non-working all call processing appears to cease.

To us it looks like voice calling is disabled on the SM-T290 and this is why the connection service method of calling fails. Is this correct? And if so, can it be re-enabled?

Why does the SM-T590 work but SM-T290 does not? Both are wifi only, and have 1 speaker and microphone.

Any help or insight will be greatly appreciated.

Thanks for sharing
Aakarsh