Ken wrote:

My question: Just out of curiosity, what do the manufacturers do to
make their same model cordless phone communicate with only the base it
belongs? My guess is they change something simple like the crystal on
both the base and handset so that there is a distinction between units.
Anyone know?? Thanks.

The early ones used different frequencies. Then when the multiple channel units
came out (in the early 1990's) they added some sort of digital encoding to the
signal (such as a low level digital subcarrier) to identify one base station
from another.

Some of the earlier phones had switches inside to set this, later ones were
just hard coded in a ROM somewhere or with soldered jumpers on the boards.

The digital ones just include it in the digital data stream.

Generally they are designed NOT to allow to change them so that you buy a
new one when the old one dies.

The new generation of cordless phones, DECT (there are similar but not
compatible DCT phones) are IMHO best. DECT phones are wifi friendly they
operate in a different band (1.8gHz) and listen to make sure a frequency
is NOT in use by someone else before they transmit.

They also have the ability to connect multiple handsets to the same
base station and some have the ability to roam handests between multiple
base stations.

Geoff.


--
Geoffrey S. Mendelson, N3OWJ/4X1GM
My high blood pressure medicine reduces my midichlorian count. :-(