Abstract: A strain relief attachment for attaching a telephone communication cord to a telephone test set has a line cord strain relief element, a grooved neck end of which is insertable through a tunnel through an end of the test set to a strain relief engagement cavity adjacent to a battery compartment of the test set and accessible by a battery door. The strain relief element includes a bore through which the line cord extends and a flange configured to conform with an external surface of the test set adjacent to the tunnel. The strain relief element engagement cavity is connected by a line cord passageway to the battery compartment. A wedge-shaped line cord retention plug is inserted into the strain relief engagement cavity, engaging the grooved neck of the line cord strain relief element and a wall surface of the strain relief engagement cavity.