Calling card agi security


I have a calling card script made with php and phpagi. I have blocked the fact that you use multiple phones simultaneously in an account by entering the first caller into the database and outgoing calls are made with


My problem is that it seems like it’s a way around. I suspect that it is dialed at the same time and hits just the second and then escapes the barrier. Does anyone have the same problem and possibly someone who has a solution to the problem?

This issue it is an isolated issue caused by programming logic