In the context of packet-oriented data transmission via a network, an apparatus for transmitting a sequence of data packets checks whether a packet is missing or faulty. In this case, a replacement packet is provided which is a valid packet with regard to a packet syntax which, however, has a predetermined contents characteristic. On the decoder side, a basic decoder recognizes the packet as a valid packet and decodes same, whereas an extension decoder can enable an error concealing measure on the basis of an indication in the replacement packet to the fact that this is a replacement packet, in order to provide a higher-quality audio reproduction.