TELECOM Digest OnLine - Sorted: Re: Inmates Use Intermediaries to Go Online

Re: Inmates Use Intermediaries to Go Online

Robert Bonomi (
Mon, 02 May 2005 16:51:57 -0000

In article <>, Lisa Minter
<> wrote:

> Very few prisons/jails allow inmates any use of computers at all
> because the authorities assume the prisoners will use them for
> no good. Why, who knows, they may even use web sites to try and
> drum up sympathy for their cause.


> [TELECOM Digest Editor's Note: I would like to know one thing about
> prison phone systems, which are notoriously rip-off systems. The
> prison authorities _claim_ the recipients of phone calls from
> prisoners are not allowed to use _call transfer_ or _call forwarding_
> or _three way calling_ on calls from prisoners. I guess that is
> because the end result -- the person with whom the prisoner wound
> up conversing with -- would possibly not be on the 'approved' list
> at the prison. Does the prison phone system have the technical
> capability to restrict the called party's phone in that way? For
> example, I forward my phone somewhere, then you, in prison, call me
> as we agreed on. Or, you call me from the prison, I flash the
> hook and bring someone else on the line with me. The prison says
> in their literature that is impossible. Is it really? PAT]

"Not allowed to" means "not *ALLOWED* to". <grin>

It does not mean it's "impossible", or that the prison operation can prevent
you from doing it.

Residential-line telco-based "call fowarding" is relatively easy to detect
in software, at the originating end, if you have direct SS7 interconnect.
'Internal call forwarding' within a PBX would be virtually impossible to
detect. *Most* PBX-based _external_ call-forwarding has stigmata that would
allow "generally reliable" automatic detection.

'Call transfer' is relatively easy to detect via software -- just a DSP that
looks for anything resembling a 'ring' cadence, after the initial ringing

"Three-way calling" can also be detected with a fair degree reliability by
automated instrumentation. The _absolute_ silence on the inbound channel
is 'suspicious'. it _could_ be a 'mute' button, or it could be 3-way.
Justifies 'flagging' the recorded conversation for later checking by a
'trained ear'.

What it _does_ mean is that if they catch you doing it -- and those outgoing
calls _are_ subject to monitoring by the prison -- your number can, and
probably *will* "disappear" from the 'callable numbers' list.

It is simply "if you want to get calls from us (the prison), you agree to
play by _our_ rules."

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