Cordless Phones are telephones which use one or more radio handsets in place of a wired handset.
The handsets connect wirelessly to a base station, which in turn connects to a conventional landline for calling. Unlike Wireless Cell Phones, Cordless Phones use private base stations (belonging to the land-line subscriber), and which are not shared. cordless phoness use the the frequencies 900 Mhz, 2.4 ghz and 5.8 ghz.
900 MHZ is usually best for penetrating walls and floors. 2.4 GHz is the most commonly used frequency and is used by Bluetooth. 5.8 GHz has the best clarity.
Telephone Accessories with a frequency of 5.8 Ghz generally have the best clarity but only if the the send a receive signal are both at 5.8 Ghz.
Telephone Accessories that use 2.4 gHz are competing with more land systems and there is a possiblility of more interference. Also most microwaves work in this general area.
Telephone Accessories using 900 Mhz have the greatest distnce and go through more obstacles but have poorer quality of signal.
At this point any of the Telephone Accessories will connect up with an analog but usually a digital land line, VOIP system, cable modem or T1 line.