<s>
This	O
list	B-Architecture
of	I-Architecture
telephone	I-Architecture
switches	I-Architecture
is	O
a	O
compilation	O
of	O
telephone	O
switches	O
used	O
in	O
the	O
public	O
switched	O
telephone	O
network	O
(	O
PSTN	O
)	O
or	O
in	O
large	O
enterprises	O
.	O
</s>
<s>
This	O
is	O
a	O
very	O
widely	O
deployed	O
switching	B-Device
system	I-Device
found	O
in	O
Italy	O
,	O
Germany	O
,	O
Belgium	O
,	O
Australia	O
and	O
many	O
other	O
countries	O
around	O
the	O
world	O
.	O
</s>
<s>
Automatic	O
Electric	O
started	O
producing	O
electromechanical	O
switching	B-Device
systems	I-Device
in	O
the	O
19th	O
century	O
.	O
</s>
<s>
GTD-5	B-Device
EAX	I-Device
(	O
Class	O
5	O
switch	O
,	O
many	O
in	O
use	O
today	O
,	O
was	O
the	O
primary	O
switch	O
in	O
former	O
GTE	O
exchanges	O
.	O
</s>
<s>
Strowger	B-Device
Step-by-Step	O
(	O
Strowger	B-Device
patents	O
were	O
exclusively	O
licensed	O
to	O
the	O
Automatic	O
Electric	O
Company	O
)	O
.	O
</s>
<s>
The	O
TDX	O
switch	O
was	O
a	O
joint	O
project	O
with	O
Korea	O
Telecom	O
and	O
four	O
manufacturers	O
,	O
LG	O
Electronics	O
,	O
Samsung	B-Application
Telecommunications	I-Application
,	O
Daewoo	O
Telecom	O
and	O
Hanwha	O
Telecom	O
.	O
</s>
<s>
List	O
of	O
the	O
mainly	O
electro	O
mechanical	O
switching	B-Device
systems	I-Device
from	O
Hasler	O
AG	O
Bern	O
,	O
which	O
were	O
used	O
in	O
public	O
telephone	O
network	O
in	O
Switzerland	O
for	O
many	O
decades	O
.	O
</s>
<s>
The	O
last	O
AXE-10	O
local	O
subscriber	O
were	O
migrated	O
to	O
VoIP	O
in	O
June	O
2020	O
.	O
</s>
<s>
EMS-1	O
(	O
The	O
ITEC	O
Electronic	O
Modular	O
Switch	O
is	O
an	O
electronic	O
direct	O
control	O
switching	B-Device
system	I-Device
.	O
</s>
<s>
6	O
,	O
6N1	O
,	O
6N2	O
(	O
Rotary	B-Device
,	O
French	O
adaptation	O
)	O
step	O
by	O
step	O
.	O
</s>
<s>
The	O
McBerty	O
design	O
used	O
an	O
early	O
"	O
wire	B-Algorithm
spring	I-Algorithm
relay	I-Algorithm
"	O
and	O
welded	O
piano	O
wire	O
interconnections	O
rather	O
than	O
complex	O
wire	O
multiples	O
.	O
</s>
<s>
DMS-100	B-Protocol
(	O
large	O
local	O
digital	O
Class	O
5	O
)	O
(	O
also	O
known	O
as	O
an	O
SL-100	O
when	O
used	O
as	O
CPE	O
(	O
Customer	O
Provided	O
Equipment	O
or	O
PBX	O
service	O
)	O
also	O
known	O
as	O
Centrex	O
.	O
</s>
<s>
The	O
SP1	B-Device
processor	O
was	O
constructed	O
using	O
Small	O
Scale	O
Integration	O
(	O
SSI	O
)	O
Diode	O
Transistor	O
(	O
DTL	O
)	O
Logic	O
.	O
</s>
<s>
As	O
was	O
the	O
case	O
with	O
the	O
#1ESS	O
systems	O
,	O
processors	O
and	O
memory	O
were	O
duplicated	O
with	O
automatic	O
comparison	O
of	O
processing	O
results	O
and	O
automatic	O
recovery	O
in	O
the	O
event	O
that	O
a	O
mismatch	O
was	O
discovered	O
.	O
</s>
<s>
It	O
did	O
not	O
however	O
support	O
the	O
complex	O
recovery	O
mechanism	O
provided	O
in	O
the	O
#1ESS	O
where	O
a	O
processor	O
from	O
one	O
half	O
of	O
the	O
complex	O
could	O
be	O
connected	O
to	O
a	O
mix	O
of	O
memory	O
(	O
both	O
call	O
store	O
and	O
program	O
store	O
)	O
modules	O
from	O
both	O
halves	O
of	O
the	O
complex	O
in	O
order	O
to	O
achieve	O
a	O
working	O
combination	O
.	O
</s>
<s>
A	O
SP1	B-Device
2-wire	O
variant	O
was	O
also	O
available	O
that	O
provided	O
Centrex	O
services	O
.	O
</s>
<s>
A	O
version	O
of	O
the	O
SP-1	B-Device
ESS	B-Device
that	O
could	O
provide	O
both	O
2	O
&	O
4	O
wire	O
services	O
was	O
also	O
built	O
.	O
</s>
<s>
The	O
City	O
of	O
Thunder	O
Bay	O
which	O
operated	O
its	O
own	O
Telephone	O
Company	O
installed	O
a	O
number	O
of	O
2W	O
SP1s	B-Device
.	O
</s>
<s>
Bell	O
Canada	O
operated	O
NE-1ESS	O
2	O
wire	O
switches	O
(	O
some	O
of	O
which	O
also	O
provided	O
Centrex	O
services	O
)	O
in	O
Toronto	O
,	O
Ottawa	O
and	O
Montreal	O
.	O
</s>
<s>
A	O
4W	O
NE-1ESS	O
was	O
installed	O
in	O
Thunder	O
Bay	O
to	O
provide	O
telephone	O
switching	O
services	O
(	O
SAGE	O
and	O
AUTOVON	O
)	O
for	O
USA	O
and	O
Canadian	O
bases	O
in	O
that	O
part	O
of	O
North	O
America	O
.	O
</s>
<s>
The	O
#1ESS	O
was	O
implemented	O
using	O
discrete	O
diode	O
transistor	O
logic	O
.	O
</s>
<s>
Electronic	O
Central	O
Office	O
,	O
the	O
first	O
electronic	B-Device
switching	I-Device
system	I-Device
operating	O
in	O
a	O
trial	O
in	O
Morris	O
,	O
Illinois	O
from	O
November	O
1960	O
to	O
January	O
1962	O
.	O
</s>
<s>
101	O
ESS	B-Device
,	O
a	O
TDM	O
PBX	O
system	O
installed	O
partly	O
on	O
corporate	O
premises	O
and	O
partly	O
in	O
the	O
central	O
office	O
.	O
</s>
