An outdoor emergency telephone has to work on the one day it is used, having been ignored
for years. Everything about this one is built around that: it is a die-cast aluminium alloy
housing, sealed to IP66 with a special sealing design, weatherproof, dustproof and
moisture-resistant, with a silicon keypad and a magnetic reed hook-switch so the two most
exposed moving parts have nothing to corrode or wear.
The door cover is a detail worth calling out. It orients automatically and is self-closing,
which means the telephone is sealed again after use whether or not the person who used it
thought about it - the single most common reason outdoor telephones fail is being left open.
The housing is powder coated in a UV-stabilised polyester finish so the finish does not chalk
off in sunlight, and it carries a layer of reflective label so it can be found at night. That
last point sounds cosmetic until you consider that this is emergency equipment in an unlit
tunnel.
KNTECH are direct about where these go, and the list is consistent with the engineering:
tunnels, metro, railway, LRT, speedway, marine, ships, offshore, mines, power plants and
bridges. Most metro and high-speed rail projects require IP66 telephones for emergency
communication, and the certification reflects that market - EN 50121 for railway
electromagnetic compatibility, alongside RCM AS/NZS CISPR 32, Australian communications AS/CA
S004 and equipment safety AS/NZS 60950.1:2015.
The same housing is offered as an analogue set or as a VoIP set, which is the practical
reason to standardise on it across a site. The analogue version (SP0010012) is a PSTN DTMF
telephone with RJ11 screw terminals, ringing above 70 dB(A), a maximum line distance of 7 km
and compatibility with PABX and dispatching systems on 33 to 60 V feed. The VoIP version
(SP0010032) is SIP 2.0 with G.711, G.722 and G.729 codecs, G.167/G.168 echo cancellation,
10/100BaseTX on RJ45 over Cat5e or better, powered by PoE to IEEE 802.3af Class 0 or locally
from 12 V DC at 2 W idle and 10 W maximum, configured through a web GUI, supporting DHCP or
static addressing, 802.1x network access control, STP and RSTP, and a dry-contact auxiliary
output rated 0.3 A at 125 VAC or 1 A at 30 VDC. That auxiliary contact is how these get wired
to a beacon or a barrier.
Lightning protection to ITU-T K.21 is included, which for a telephone at the end of a long
exposed copper run is not optional. Ambient operating range for the analogue version is -30 to
+60 degrees C at 10 to 95 percent relative humidity. There is an optional seven-minute timeout
to release the line if a handset is left off-hook - which on a public emergency telephone
happens constantly - and an option for line integrity wiring so the system can confirm the
unit is still alive.
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