How to implement one way Whatsapp billing of data

Hi i have a question, i have an idea to implement one way whatsapp billing in a telecoms company. So only the caller has to have data to be able to initiate calls. Even if the recipient has no data the call will go through and bill the caller double or a fixed higher price. The engineer at the telecoms company i pitched this to is asking some technical questions on how this might be implemented, your advice is valued.

I am the engineer responsible for these sort of issues boss. Let’s have the architecture on how you see your system/app sitting in the value chain on making a WhatsApp call. Remember we have nodes that are already within the value chain i.e from your billing engine, your gateways(charging), policy control etc, we would want to know where we place your app so we see how it interacts with the existing nodes and possibly what changes can be made for us to achieve the desired result.