Is there an easy way of blocking a caller? I have only found a way of doing this by adding a task but that will complicate the building of the whole IVR. It would be great if you could add a task before the Main Menu that will be checked.

F.eg. 

TASK (Block Caller.ANI)

     Main Menu

             Press 1 ABC

             Press 2 DEF

             Press 3 GHI

     Disconnect

You can set a task to run before a menu. Drag a task to the Reusable Tasks section and then you should see a button called "Set this as the starting task" on the details of that task. Be sure to remember to  end the task with a "Jump to Menu" action.

Something like this could work in a Decision action. On the Yes branch do the Jump To Menu and on the No branch do the blocking processing.

FindFirst(Task.blockedNumbers, Call.Ani) == -1

Task.blockedNumbers would be a collection variable and either fetched with a Call Bridge Action or maintained in the flow with an Update Data action as the first action.