If someone rings your doorbell and you don't know who rings your doorbell, you should buy a QR sticker for doorbell safety from Nekinsan. This QR sticker will help you to know who is ringing your doorbell, for example, someone who rings your doorbell they scan your QR doorbell and make a video call or normal call to you. The benefit part about this is you can use this QR sticker in your house or office. In any case, someone has no internet in their cell phone so they directly switch their video call into an audio call by scanning the QR sticker. There are many ways to connect to others, and in some cases, if someone rings your doorbell and does not have a smartphone or internet he dials the helpline number which is mentioned in the QR sticker, and gets connected with your numbers through an IVR call.