The combination device includes a first pair of series coupled first and second magnetically coupled coils, to which a first DSL line and a first DSL transmission line are electrically coupled, and a second pair of series coupled first and second magnetically coupled coils, to which a second DSL line and a second DSL transmission line are electrically coupled. A third DSL line is coupled to a first coupling element between the first and the second coils of the first pair, and to a second coupling element between the first and the second coils of the second pair. The combination device is located in a phantom injection module provided with at least five terminals respectively associated to the first DSL line, the second DSL line, the third DSL line, the first DSL transmission line and the second DSL transmission line.