The microfilter strips the DSL signal from the phone line. Using a microfilter on the line going to the DSL bridge (modem) means that you will NEVER GET SYNC. EVER. Please read the information that came with the system. The microfilter goes on all ANALOG devices
Microfilters trap or block a specified frequency in this case the range that ADSL runs at. The voice portion of your phone service works at a lower frequency than DSL. DSL is a high frequency signal so the lines with the POTS connections (POTS=Plain old Telephone service) has to have a filter on it if it shares the same line as the ADSL service. If not then you should hear a bunch of hissing and heavy white noise like when the station goes off on a TV set and you see and hear the static.
The multiple high frequency carriers beating against each other cause hissing on an unfiltered DSL line. This is a fairly even and steady hiss with no pops or crackles. Filtering the high frequencies will thus stop this hissing.
Hissing that is not stopped by filters would have another cause. Static -- sharp crackles somewhat like the crumpling of cellophane -- is *always* bad. Usually caused by faulty wiring. Whatever is causing the static *will* knock your DSL. This could be a phone. Unplug all your phones and faxes and modems; plug in a known (tested at a neighbor) good phone and test. If quiet, plug in devices until the noise returns. Remove faulty device from service. Else, if you are on the wire plan (pay your $1/month or so for coverage of inside wire and jacks) call 611 voice repair and tell them you have a problem with your line. Else, disconnect all of your premise wiring from the protector and test with your known good phone at that point. If quiet, tie IWs down one at a time to find the culprit. Replace or retire the faulty IW. Else, call 611 and tell them you have a noisy loop.


Item in lower right is a Line Swapper. It is used to swap the red/green pair with the yellow/black. ( 2 and 3 with 1 and 4).

You can also call 1-800-VERIZON (837-4966) for repair.