Windows Legacy App: The number disappears from the input field, and after a short period of non-response, a dial tone rings.

[C-SP]

As a premise：
Using a Windows Legacy App because it is mandatory to use BLF.

Issue：
When I enter a phone number and press the "CALL" button, the number disappears from the input field, and after a short period of non-response, a dial tone rings.
As a result, it is difficult to determine where the call is being made and whether the call is being made correctly.

Is there a setting or registry change or something to fix this lag?
I would like to know if there is any countermeasure.

 

[C-SP]

I would be grateful if you could let us have your answer concerning this matter.
Please let me know if you need more information concerning this matter.