Abstract: The object of the invention is a method for emulating the two-way information flow of a real application in a system, which comprises a first network element (101) and a second network element (102), as well as a packet network (103) between said first network element and said second network element. The method comprises transmitting a set of packets from the first network element (101) through the packet network (103) to the second network element (102). At the second network element, at least part of the transmitted packets are received. The received packets are transmitted from the second network element (102) through the packet network (103) back to the first network element (101) in response to the receiving of the packets at the second network element (102). In said return transmission, a packet arrived at the second network element is transmitted back to the first network element only after a delay from the receiving of the packet at the second network element.