Amateur stations and broadcast stations accounted for the other half. The power levels used by the radio transmitting station did not appear to be a significant factor in causing telephone interference. Power levels of 10 watts or less caused telephone interference in a third of the cases. A large portion of the residential telephones appeared to be susceptible to interference from nearby radio transmitting stations. Although some telephones did not receive interference, the limited nature of the testing performed in conjunction with this survey would not support the conclusion that they would always reject interference.
Manufacturers can, however, design telephones to be interference-free.
Notwithstanding the 25,000 reports of telephone interference the FCC receives annually, it is FOB's experience that, as large as this number is, it probably represents only a fraction of the actual instances in which this interference occurs. Given the enormous numbers of instances in which this type of interference is experienced by consumers, it is our hope that this survey, notwithstanding its informality, will serve as a catalyst for affected parties to productively address and resolve this problem. As always, FOB remains ready to assist in that effort. This list does not include 11 telephones which received interference in one case, but did not receive it in another case. This list does not include 11 telephones which received interference in one case, but did not receive it in another case.