1A2 phone system

From: Doug Carman <pdp11_at_bellsouth.net>
Date: Wed Mar 13 14:07:09 2002

Empirephone_at_aol.com wrote:
> Have a 1A2 phone system and I am having a hard time restricting the
> phones from dialing out without disabling the key pad. Is there any
> way I can program or wire the phone so that I can disable it from
> making outside phone calls??
> Let me know
> Sid

Maybe there should be a "Classic Communication" list.

The short answer is no. 1A2 key phones have tip and ring of the outside
lines connected directly to the phone, with the addition of 'A' leads
for control and 'Lamp' leads to light the busy lamp. Once the line key
is pressed, the phone operates much the same as a single-line phone.
This is what allows the phones to be used when there is no power,
because the rest of the key system really isn't needed for the phone to
be used for placing a call. As long as the dial is connected, you can
dial any number that the selected line is allowed to call.

That's where the problem really exists. In order to provide
restriction, you need to restrict specific lines either through telco
provided restrictions, or through external devices that listen to the
digits being dialed and disconnect the line if someone tries to make a
call that is not allowed. External "toll restrictors" are not common
anymore because the assumption that all toll calls start with the digit
'1' is not always true and these devices were not always sophisticated
enough to do the job.

So, you could ask the telephone company to put toll restriction on your
lines, except for a select few that are separate and not part of the
inbound hunt group. The non-restricted lines would be made to appear
only on the phones of people that need to make toll calls. The lines
that are common to all the phones would be restricted. That was a
common arrangement before the days of electronic key systems with
sophisticated programming features. People even used to put key-switch
locks on the phones that were wired to disable the dial so that someone
couldn't make unauthorized calls if they had physical access to the

Doug Carman
pdp11 at bellsouth dot net
Received on Wed Mar 13 2002 - 14:07:09 GMT

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