A data communication cable can comprise multiple pairs of twisted conductors. A jacket that extends along the outside surface of the cable can define a longitudinal core, internal to the cable. The conductor pairs can be disposed in the core of the cable along with a foam matrix or a porous filler, with the matrix and the conductors occupying essentially all of the volume of the core. The foam matrix can hold each conductor pair in a respective location within the cable core to control signal crosstalk on each pair. A co-extrusion process can produce the cable via simultaneously extruding the foam matrix and the jacket. A pulling apparatus can feed the conductor pairs though respective ports of an extrusion head-and-die assembly. As one extruder encases the moving conductor pairs in the foam matrix, another extruder forms the jacket over the matrix and the embedded conductors.