Once visitor comes and push the call button, you can open the door inside using videophone or interphone.

客户来访，按CALL按钮，您可以使用对讲电话给客户开门。

youdao

Once visitor comes and push the call button, you can open the door inside using videophone or interphone.

客户来访，按CALL按钮，您可以使用对讲电话给客户开门。

youdao