It simply consists of a 2.2mH choke in both lines.

Like these
http://uk.farnell.com/jsp/endecaSear...jsp?SKU=432167

I'll post a pic in abse.

I'd expect a common mode choke to be better of course.



I *hope* they use a more appropriate choke than that one-- if you read
down a bit the specs say it resonates at around 1.35 MHz. That means
it's more of a capacitor than anything else above that frequency, and
not a very good inductor in the AM band. Although likely to be good
enough at the lower DSL frequencies.

A good 2.5mH RF choke is pie wound to minimize capacitance and is good
up to 30MHz at least.

Opening up a DSL filter here shows a somewhat better design -- a two
solenoid-wound chokes and two mylar capacitors across each end.

But that still is not quite optimum-- the DSL frequencies that filter
tries to choke out are not quite as high as the AM BC band. SO a pair
of *good* RF chokes will probably work better than the DSL filter type
of chokes.