Cancelling an overlay will stop all future calls going to that destination. You may want to stop providing calls to a destination, or free up overlays that are rarely used to preserve numbers for other overlays.
To cancel an overlay you must identify it; this can be done either by providing the DNI ADNOS returned when creating the overlay or by sending the infomration initially used to request it (reference string, DDI, class and advertiser).
Note, This will cancel the overlay, stopping future calls. Calls already in progress will not be affected. This does not stop calls ever reaching the destination, if you request an overlay for the destination again one will be created however the DNI may be different.
If we wish to remove the overlay created in the previous example, we simply provide the same class and reference string, but a different destination number.