As with all scientific papers, this has to be taken with a grain of salt. The assumptions of this paper about the way speech is encoded, encrypted and fragment

As with all scientific papers, this has to be taken with a grain of salt. The assumptions of this paper about the way speech is encoded, encrypted and fragmented are quite extensive. For example, the need for a vbr-codec for this method to work is a deal breaker. Most consumer grade voip is not compressed a lot (considering that 64kbit/s isn't a big deal nowadays) and definitely not using a vbr codec (e.g. G.711 is used quite often, a cbr codec). So, at least for this method, encrypted VoIP data is usually secure.