Abstract: The present invention relates to echo suppression in a telephony system wherein a communication link is established over an analogue network and a digital network. The disclosed echo suppression invention provides cost-effective ways of minimizing an echo arising in the public switched telephone network (PSTN) by calculating a first value for the energy level of the signal from the analogue to the digital network, and likewise calculating a second value for the energy level of the signal from the digital to the analogue network. The sound from the analogue network to digital network is transmitted in dependence of the results of a comparison between the first and second values.