In such cases, one or more of the shunt capacitors across the telephone line end of the filter can be eliminated. To do this, connect two inductors in series, per side, with a third capacitor across their midpoints, as shown below. To completely eliminate RFI, such telephones can be placed inside a shielded metal box, along with the person using the telephone. This is not very practicable, so the best solution may be to discard the telephone. Reportedly, a wooden stake and a hammer cures the problem every time.
More turns are usually better.
This test should be repeated on each offending telephone after RF filtering is installed. Thus, it may be necessary to install a filter on the telephone line input wires near the modular socket on the base unit, and install another filter in the handset. Desk type telephones, in which the dialing and ringer circuits are in the same enclosure, are usually easier to RF-proof. The fix is to solder the splices or coat them with silver conductive paint. The capacitors are for tuning out the inductive-reactance of the ground lead on the troublesome band.