Issue in make a phone call within Google Assistant App

Question

I try to implement button in basic card i got an error

API Version 2: Failed to parse JSON response string with \'INVALID_ARGUMENT\' error: \"(expected_i

Answer 1

You cannot open a tel: URL through the Assistant.

As the error noted:

expected_inputs[0].input_prompt.rich_initial_prompt.items[1].basic_card.buttons[0].open_url_action: the protocol must be http or https.

Keep in mind that the Assistant runs on devices that do not support tel: URLs, even if they support https: URLs.