"Two Bob" <dept9@iprimus.com.au> wrote in message
news:4636e6e8$1_1@news.iprimus.com.au...
>> g'day,
>>
>> The role I do includes monitoring various sites for plant and
>> intruder alarms. I work 2200~0600.
>>
>> Some sites use GSM as a backup to their standard dialler.
>>
>> I have some questions regarding the behaviour of these systems
>> I hope somebody can answer, or at least direct me to a more
>> appropriate ng.
>>
>> Occassionally these networks fail. We then ring people to advise
>> them of this. It would be nice (when ringing someone at 0245) to
>> be able to offer some reasoning for these failures. I can ring the
>> mobile in question and hear it chirping, and for eg.. I wonder,
>> well, if it answered, why is it appearing to be offline, or failed?
>>
>> Can rain be a cause for these failures.
>>
>> Or is mobile tower / repeater location (dropping in and out of
>> signal range) a more likely cause?
>>
>
> My guess is that when the unit dialled in, the codes got scrambled via
> distortion, causing the base to miss the sign on code therefore not
> recognising that it was armed. Maybe relocate the aerial to a better spot.
> GSM, being a backup system shouldn't be used except for when the main line
> goes down. Best to interigate the system via landline and if everything is
> OK then treat the GSM signal as missing a beat.



Thanks to all that replied, to this point. Most useful.