Just to clarifi
If theres an issue with the dsl signal the typical cause is the internal wiring. and the most common cause here is the bell wire.
The newer openreach logoed nte's have a small suppessor in the face plate for the bell wire
The I-plate is a retro fit plate which any end user can fit themselves
IF the bellwire is causing a difference in performance then the same suppressor comes into effect due to the I-plate with an older nte.
If the other 2 wires are causing a performance issue then the full dsl-ssfp front plate can be used, this plate takes care of any issues with the bell wire and the other 2 wires. the I-plate wouldn't make any difference here.
Either front plate means with the bell wire connected your extention sockets will still ring, dissconecting the bell wire with one of these plates will make no difference to your dsl signal (except with the exception of a few phones, none will ring in an extention on an incomming call with tis wire disconnected)
"Do I need either type of front plate?" First have you any extentions comming from the master socket, if no the you don't need the plate.
Do you get a difference in performance by plugging your router/modem into the test socket in comparison to the extentions connected, then yes one of the plates may make a difference.
To find out which you need, disconnect any bell wires (in termination no.3) and try your broadband with the extentions connected. If the result is the same as the results in the test socket, you need the I-plate, if dissconnecting thebell wire only hasn't given the same result as in the test socket, you need the full dsl-ssfp
Either plate you'lld want the bellwire connected
If you find you do get a satisfactory result by disconnecting the bell wire with the extentions connected then you can leave the bell wire disconnected before you get your hands on either plate, you'll still get the phones ringing in the extentions if you still have your microfilters plugged-in
