I need a PHP application to receive and send whatsapp messages from a web interface.

The web app must monitor a given mobile number in order to receive all whatsapp messages and allow a custom answer to any of them via web interface. We will not send bulk messages at once, but still the app must not get blocked so it must emulate natural writing and delivery.

I'm looking for someone that has already developed similar solutions with proven experience managing whatsapp interfaces so please send an estimation of the total hours for this project considering the following requirements:

Version 1:

- Login page. The application will be hosted in a web server and will have a unique login and password.
- Dashboard. The dashboard will show a table with the opened conversations that the Whatsapp user / mobile phone number, has currently, in a similar way as an inbox view of an email. Name and phone of the person with whom my number is having a conversation with, bold if there are any messages I haven't read in that conversation, date of the last message. Something like this, we can define it a bit more later.
- Conversation View. A simple conversation view that allows to see all messages sent and received, their status (sent one check, read two checks) and also an interface to reply with text. It is important to know if I can also reply with clickable Links or attach images from my PC with this API, it is very important for me to be able to attach images.
- Settings View. A simple settings panel to set up my name, picture, phone number and anything that may be needed for support and maintenance of the tool.

Once we have Version 1 ready and tested working, we can proceed to version 2. For version 2 I have more features but I need first to estimate version 1. However if you can provide some information regarding all limitation of the number of messages and number of contacts per one mobile phone without the Whatsapp number being banned, since this is important for version 2 and this, this will be of good value for your proposition and a prove of your existing experience.