Este dá uma explicação decente do motivo pelo qual o ATM foi projetado como um protocolo assíncrono.
Though TDM is very efficient carrying delay sensitive voice traffic, it wastes bandwidth because individual time slots in the synchronous frame cannot be easily reallocated in real time between variable and constant bit rate traffic sources. By the late sixties, researchers at Bell Labs had the idea of introducing a label into each cell to identify traffic sources. Thus, a given call would be transported by an asynchronous series of fixed length cells identified by a virtual circuit identifier in the header, instead of being assigned to a fixed time slot.