Annex B is the current standard for digital subscriber line (DSL) in Germany. A DSL-splitter is an analog L-C-filter to separate the POTS (plain old telephone service, like voice and ISDN, FAX) signals from the DSL signal.
Is the DSL-splitter required, if no devices but a DSL-Modem is connected to the line?
If yes, one could test if a splitter is faulty by connecting the Modem direct to the line. The bandwidth should be similar in both situations.
42 Answers
A DSL filter performs 2 functions:
To prevent DSL frequencies from reaching non-DSL devices
To prevent spurious noise from non-DSL devices from interfering with DSL frequencies
If there are no non-DSL devices on the line then no filter is required.
2Reference ADSL Filters & Splitters
You should use a filter anyway. The filter performs two main functions:
Prevents the ADSL signal interfering with the voice part of your phone line (not required in your case as you have no phone connected)
Ensures that the ADSL line is terminated correctly. An unmatched termination may cause reflections back down the line. This can cause errors on the ADSL connection.
