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TUCoPS :: Phreaking General Information :: xchange.txt

The Arcane art of Finding UXD5b Switches

The Arcane art of Finding UXD5b Switches                By Keltic Phr0st

The UXD5b Switch is a 600 line Rural Telephone Exchange Mechanism based
around a basic Reed-Switching frame under MicroProcessor Control.
It allows for On-site Maintennance via a CSS Teminal located within
the Exchange Building, and has provision for external maintenance via
a dedicated dial-in service running at 2400bps.
        This Provides the user or field Engineer with all the facilities
he or she needs to control the switch processes, and check on system status.
A line is also provided for Operator usage. 

        This is the line we are interested in : The one linking the UXD to
the outside world. It is tied into a part of the system designated the OSS
or Operator Sub System, and allows full operator control over the exchange
in question.

Finding and determining Exchange type
Take a look in your phone book. Look for numbers that are listed as
Three figure or six figure numbers. They should be presented as so:


Where X is the Subscribers Directory No. Look for two numbers on the same
exchange that have the same first eight digits. If that holds true, then
congratulations, you may have found one.

Get a pen and paper, and a DTMF Dialler. Pick up your phone and start 
dialling. Try these numbers:

        299   Should ring long, short, Long short
        370   Plays 404hz like USA Ringer
        394   May play constant 404hz or 1633hz
        395   May play constant 404hz or 1633hz
        403   Should ring out
        720   Should be busy
        721   Should get carrier at 2400
        174   Issues 404hz, Rings back (Faultsman Ringback)
        175   Should do Nothing (SALT)
        176   Should do Nothing (Line Check)

299 : Labelled as 'UXD Test Number' on Main Distribution Frame Records
      Should hold true for most exchanges.
370 : Labelled as 'MAC Test Number' on Main Distribution Frame Records
      Possibly Manual Access Controller?
      (NB : Measurement and Analysis Centre Interface)
394 : Labelled as 'Gateway H O/G' on MDF Records.
      Alarm Extension Outgoing
395 : Labelled as 'Gateway H I/C' on MDF Records
      Alarm Extension Incoming  
403 : Labelled as an Internal Number. This is the number of the phone
      designated for Engineer use within the Exchange. DO NOT ring this
      during the daytime. Could vary from Exchange to Exchange.
720 : Labelled as Routiner Answer Relay Set (Routiner Access)
      Could be dedicated Data link to X25 or simple leased line for
      Dial in Maintennance. Permanently engaged.
721 : Carrier at 2400. This is the decider. If none of the above worked,
      but this does, then you have struck gold.

The Exchange I tested fully was only handling 272 subscribers, listed 
200 to 400/450. The number range 000-200 is kept free for test numbers and 
like, and the upper empty range used for various BT Equipment, mostly held
in 7XX. A few test numbers are allocated next to subscribers for some
reason. Looking at the CASS Printout for your exchange (If you find it
through trashing) will list all numbers of Intrest as connected, but with
a Batch Metre Reading of 00-000000000. Normal Subscribers have their Batch 
Meters running, taking into Account line rental and billing.

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