From the schematic and performance parameters, these look like transient clamps. They will not improve the performance except for protecting your data terminal equipment from damage by lightning strikes on the telephone wires.
The 10 J is ten Jules of energy absorption capability without destruction. The 160 V rms is the potential that will just start the protective devices drawing current. These devices may be gas tubes or MOV types. These devices are less costly than the equivalent Zener and operate on both polarities.