A method of improving sound playback of digitized speech signals transmitted to a telecommunications terminal at the beginning of a telephone call set up over a communications network where the signals are transmitted in the form of packets, and in particular at the beginning of a VOIP call set up under Internet protocol, at the time said call is set up from a sending telecommunications terminal fitted with voice activity detection means so as to be capable of transmitting only those digitized signal packets that contain speech taken from a set of sound signals that are suitable for being transmitted in the form of packets after the sound has been digitized and encoded in the sending terminal. Signal packets are transmitted from the digitizing and encoding means during an initial call optimization stage without taking account of whether or not any speech signals are present. The invention also provides telecommunications hardware implementing the method.