am looking for a cost effective solution where in I want to initiate a call by entering a code or scanning QR code from a mobile phone which does not have any applications installed. The user should be able to scan a QR code and press the button in the web page which is getting loaded while you scan the QR code. On pressing the button there should be a video call that has to be initiated which should get landed to a pre installed Android or iOS app (developed in flutter) and the talks should be completed smoothly.

Precisely the solution shall be this developed app and back end of any, that shall be installed by the user and a linking and connecting to a code. This code will be generated by any user while installing and registering the application in any standard Android or iOS phones and the call should be connected.

I am looking for a very cost effective solution as this is going to be deployed free for all users. I am looking for individuals or companys who have experienced in developing similar applications and can provide the solution at a very low cost budget. I will not be interested to discuss with anyone who provide the quotation at very low cost for the sake of discussion and later on change the same.

For your reference, a similar solution can be checked here.

DoorVi Smart Video Doorbell Powered by QR Code Technology | Instant Visitor Video Call on Smartphone | QR Scannable Technology | 2-Way Talk [login to view URL]