Do you intend this to work with any GSM phone with any configuration, or
do you have control over the phone's configuration?

The former would be considered intercepting a phone conversation, and
outside of legal issues which differ from country to country, I suspect
that the system has built in functionality to prevent someone from
simply setting up a cell site that is 'unregistered' or doesn't have the
proper keys (or however such functionality might work) to communicate
with a GSM phone not configured for use with that cell site.

I'd appreciate being proven wrong, however, as this would be quite a
vulnerability to the system.  Just think of the opportunities - I could
drive through downtown with my mobile cell site, and as phones switched
off to my 'tower' I could give them a short commercial until I was out
of range.  If their phone and their provider's system is robust enough
they may actually be connected to their previous conversation... but
probably not.

It'd also be easy to set one up in a theater, with a brief message about
not using cell phones in the theater.  etc, etc, etc.

If it's the latter, then I bet you'll have to bite the bullet and go for
the cheapest full tower setup you can get, and configure both the phone
and the tower to talk to each other.

Please let us know how your project goes...

-Adam

Russell McMahon wrote:

>>From your posts it isn't clear whether your ultimate product is on the
>>
>>
>'cell
>
>
>>end' or on the 'phone end' of the link.
>>
>>
>
>Ultimate product was not made clear :-).
>But here's the desired functioanlity in more detail (from an offlist answer
>to anothe rrespondent),.
>_________________
>
>I don't want to give the phone a real network - just make it think is has
>one. ie the functionality I would like is "call it from the black box and it
>rings and answers, call anyome from the phone and the black box handset
>answers." ie
>
>- On power on phone can wake up and see there is a (single) network signal
>present (or not)
>
>- if present it negotiates network access as usual.
>Some of what it is told may be lies - as long as it doesn't know.
>
>- If no signal present it sits there declaring no signal until signal
>appears.
>
>- If it makes a basic call to *anyone* it will SEEM to work - the call will
>actually be terminated to a handset on the nano-cell-site. They will not
>know, senor.
>
>- If one wants to call it, it will see a standard "ringing" or whatever
>signal with its ID therein. Answering protocol negototiated. Lies told as
>required as long as it effectively doesn''t know.
>
>- If there are more complex modes available they need not be implemented.
>Good old apparent POTS is all that is required. SMS, GPRS, WAP  etc not
>needed.
>
>Any suggestion as to MINIMUM components from a full system that could be
>persuaded to do the above would be useful.
>
>__________________
>
>
>
>
>>I know this doesn't answer the
>>question you asked, but if you just need to communicate with a GSM module
>>
>>
>so
>
>
>>you can build a device around it, most of the service providers have cheap
>>developer programs that will give you access to your phone/module via
>>
>>
>their
>
>
>>servers.
>>
>>You might call the guys at Ramsey Electronics and see what they suggest -
>>they make test base stations for pagers - maybe GSM is on their list of
>>current projects?  www.ramseyelectronics.com
>>
>>
>
>Thanks - I'll check such leads.
>
>
>        Russell McMahon
>
>--
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>
>
>
>
>

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