Inside a Telephone Exchange

Have you ever wondered what goes on 
behind the scenes of your telephone exchange?

What does all this jargon-ADSL, DSLAM, VOIP, ROUTER, actually look like?

As many of you may not know Nightwalkerbiz's Head Sysop, worked in Telstra as a Super User Network Technician.

We had access to all area's, and worked in many exchanges and have dug out a few photo's of inside

of a local exchange, that have been collected by colleages and the like over time.

Above: Customer side of the Main Distribution Frame at a
main telephone exchange

Lots and lots of phone lines

Avove: NEC AM-31 DSLAM

High capacity ADSL DSLAM

Above: ADSL testing at the MDF
Testing a customer's ADSL service at the main distribution frame of a telephone exchange.
This is the "customer" side of the MDF, with the ADSL DSLAM located in the next room.


ADSL Digital Subscriber Line Access Multiplexers from a variety of ISP's -
IInet, TPG, Optus, AAPT & IPrimus


Huawei DSLAM, provides TPG ADSL2+ service

You have probably read in the news about the
Australian Goverment not allowing China's
equipment to be used here, well above is the
said equipment they are so scared about.

Cisco 10000 series Universal Broadband Routers (HFC)

4x Cisco 10K UBRs and associated RF gear to the right. These DOCSIS3 UBR's act as the modem termination point for cable broadband customers. This exchange acts as the parent site for a large number of cable customer connections.


Left: DSLAM cabinets

Various ISP DSLAM cabinets in the regional telephone exchange.

You have probably been told many times there are no Telstra ports available,
but Iprimus or TPG, will have ports available due to them
having their own DLSAM's.
And usually these type of ISP's now seem to have much more
equipment than Telstra do.
Well now you know what they look like.
Just look below to see a naked one, without the cabinet.


   Left: Alactel-Lucent 7300 ASAM DSLAM

Exchange-based high density digital subscriber line access multiplexer with 3 subracks - 24 or 96 pairs (ADSL services or "ports") per connector.

Here you can actually see the ports you connect into for your ADSL2+


 Tellabs 8800 Multiservice routers

Tellabs 8800 MSR's at a main transmission site with a mix of E1, Frame Relay, Gigabit Ethernet, STM-1 and STM-4 interfaces (electrical and optical).

These provide intrastate transport/backhaul for customer and internal services. ADSL DSLAMs commonly feed into these via STM-1 connections for backhaul to BRASs.


Backup batteries in case of exchange power loss

These batteries will provide about 10-12 hours of power supply 

in the event of mains power failure.

This is why you never loose your telephone line or ADSL in a power failure,due to them 

having a backup supply for emergencies.

 We at Nightwalkerbiz must have similar backup power supplies,

but in our case we  not only use battery banks for emergency use,

but use auto switching to huge deisel power generators for continuous power supply.


Above: Ericsson GSM RBS200 mobile
basestation left and WCDMA RBS3206
mobile basestation to the right.

Ericsson mobile basestations for 3G

and 4G mobile services.

Coaxial cable runs go up to flat panel

antennas on roof of building.

VOIP Session Border Controllers

A pair of SIP Session Border Controllers for VOIP.

This is the controllers for the Voice over IP

phone systems some ISP's supply so you can talk

for free over the internet.


The big green boxes you see in the street, have you ever wondered what they were? 
These boxes house your ADSL2+ internet and telephone supply from the exchange.

ADSL2+ DSLAMs are being built into a housing which is ingeniously being mounted to a
pre-existing streetside cabinet (RIM or CMUX) which services the surrounding streets.
Thus the name "tophat".

This will enable home broadband (ADSL2+) to areas for the first time whilst also installing additional ports (ADSL2+)
in numerous locations that have "no spare ports".
These are mini exchanges located in the street, not unlike the main exchange that houses very similar hardware.

Telstra is splitting up Distribution area's, to service what they can't in the exchange.
 Basically an ESA (your exchange service area) is split up into multple DA's.
A tophat may serve one or more DA's dependent on size of DA,
these mini exchanges utilse gigabit ethernet to each tophat.