Are the 420 telephones compatible with plain old telephones (POTs)?
A. In most cases, yes. POTs will activate the line-in-use indicators on the 420 telephones. However, calls cannot be transferred to POTs, nor can intercom calls be made. Some inexpensive telephones may interfere with the 420 system communication. A filter (Radio Shack part number 43-150) may be required if a POT is connected to the system and system functions do not seem to be working properly. Q. Can I connect another manufacturers KSU-less telephones to a 420 system? A. It is not recommended. Other manufacturers KSU-less telephones may interfere with the 420 communication over line one. Q: What is a reliable FKS? A: FKS is an acronym for Frequency Key Shifting.. FKS is the technology that all telephone service providers in the U.S. use to send a signal down the phone line to indicate to your phone (lights your voice mail indication light) that a message is waiting on your service provider’s voicemail system (assuming you have subscribed to this service). The 420i has the industry’s l
