They must be viewing the bellwire as a substantial cause of adsl problems to be introducing this device instead of focusing on the full filtered NTE5 faceplates, and that once the bellwire is filtered out it fixes the a large proportion of faults caused by the internal wiring. Yes, it is a self install device, but unless it was having a major impact, why would they bother with issuing it ?
Interesting. I wonder, when comparing faults cured by this bellwire filter vrs faults not cured by bellwire filter but fixed bt NTE5 filtered faceplate, I wonder what the actual percentage will turn out to be. Imagine if it turn out that something like 90% are caused by the bellwire.