In spite of the optimism of the recent years, packet-based comprehensive communication is still not a reality. Among others, significant technical roadblocks are standing in the way of such a reality. This paper develops a taxonomy of the domain and positions the research opportunities that exist across this domain. Significant breakthroughs in the areas outlined in the paper are necessary to enable the advent of comprehensive and ubiquitous packet-based communication with high service quality. Of course, the required economic and social considerations are outside the scope of this paper.