"Jam Man" <dajamdaddy@yahoo.com.au> wrote in message news:JhzZh.31966$M.17872@news-server.bigpond.net.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?
>
> Can the cold (written with a straight face) be a factor to reception?
>
> Questions may appear silly but they are asked in seriousness. You
> may have experienced people, as a part of your job being on call,
> calling you at 3am. It's a pain, at best. It's not much fun making
> those calls either just quietly. Just trying to improve my
> understanding of how the GSM networks report to us,.
>
> cheers
>
> da jam daddy
>

I've worked on networks with GSM backup, but it was only there for accessing the alarm, power and control system in the event of transmission loss.
It's not actually a backup for the transmission, it's just a backdoor to the control system. It doesn't carry the traffic of the given base station.
Actually dialing the sims number with another phone would be useless (there's no actual phone onsite just a little black box with a sim in it) it had to be connected through a router then you could interrogate the individual network elements using their ip addresses. So being able to communicate with the site doesn't mean the site is communicating with the rest of the network.
If the transmission is by way of microwave, then yes weather can play a part in losses/ failure. And the reasons for a site failing are really varied, power outage, bird /vermin attack, weather, vandalism, fire etc etc etc...
With a better knowledge of how the network is put together and how it works, comes a better ability to read the failure conditions and therefore diagnose probable causes before you ring the oncall guy. The best way i know to gain that knowledge is to /be/ the oncall guy for a while.

H