This doesn't require a permission.
val intent = Intent(Intent.ACTION_DIAL, Uri.parse("tel:+123456"))
startActivity(intent)
Or
val intent = Intent(Intent.ACTION_DIAL, Uri.fromParts("tel", "+123456", null))
startActivity(intent)
But it shows one more dialog (asking whether you want to call phone just once or always). So it would be better to use ACTION_CALL
with a permission (see Revoked permission android.permission.CALL_PHONE).