BT junction box with built in REIN filter. The built in filter is designed to reduce induced electrical noise which can not only affect telephones but also broadband modems/routers. This often results in improved syc speeds due to less line disconnects which with VDSL = improved speeds! (ADSL lines can also benefit from this filter but you may need to contact your ISP to request a reset of the line so re-training can commence).
Simply install upstream of the master socket using the screw & IDC terminals (IDC tool also available). If required the filter can be installed immediately AFTER the master socket if the subsequent extension is then feeding the modem/router.
The filter (inductor) in this junction box is the same as the one fitted to the (now discontinued!) BT I Plate/BT Broadband Accelerator . Fit to eliminate small Repetitive Electrical Impulse Noise (REIN) which can affect broad band VDSL/ADSL lines. Dimensions (L) 56mm x (W) 41mm x (H) 22mm.
Note, the Mk3 vDSL SSFP & Mk4 SSFP feature a filter that is similar to the BT80B RF3, however it is NOT identical. The existing stand-alone RF3 may still be required to assist in solving REIN faults and can be fitted even when the MK2/MK3 & MK4 VDSL SSFP is in situ.