I need to build a system where people will use a payment gateway (like Stripe and Paypal) on my website to buy minutes of conversation associated to their own telephone number. Once they pay, 3CX must associate the amount of minutes to their telephone number. When somebody call to our telephone number, 3CX must allow him to talk to our operators only if there are minutes of conversation associated to the caller telephone number. Once a person is in a conversation but his conversation minutes expire, then the call must drop.
For example, if a random telephone number calls our number, it must not be allowed to talk to our operators.
If a certain telephone number purchased 20 minutes of conversation on our website, it can call and talk to our operator for a maximum of 20 minutes, even split into more than 1 call. For instance, it can make 4 calls split into 5,10,3 and 2 minutes of conversation each.