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Back in the day, almost all cell phones had a miniature coax port on them. They were "hidden" in that you probably had to pry off some nondescript part or open the battery cover up or something.

This is how we tested mobile networks. It works great. The only problem is when someone forgets to make a tight connection or attach a signal attenuator. Since the first thing you always test is emergency calls, once in a while your call ends up on the real mobile network and the fire department shows up in your parking lot. This happened about once or twice a month where I worked. They knew what our business was so they were never mad at us, but we had to pay a fine each time.



It’s not only how they tested mobile networks.

The old Nokia and Ericsson phones as well I think as some Motorola’s had a rubber plug in the back just below the external antenna with a coax port that you had to remove when you plugged the phone into the a car speaker phone system the phone would then hook to an external or a larger antenna glued to the windshield.


You know I remember a Motorola v120 having that. It appears that's what it was.


Interesting, that must be why the coax port survived from engineering to production.


The external port was a requirement for kits like this

https://images-na.ssl-images-amazon.com/images/I/411PQXERG6L...

But signal testing kits also used it.

This survived until 2G the 5110 still had it.

When 3G came out the coverage was good enough and I’m guessing that issues with signal strength in cars was more or less solved.


What a blast from the past... I remember installing that exact kit (plus antenna) in my own car some twenty years ago. It worked great.


Nowadays you can use also use the built-in modem: open the telephone app and type this:

    *3001#12345#*
then tap Call


What does it do?


iPhone’s “Field Test” debug screen: Dial 3001#12345# for the real signal strength [0]

[0] https://ma.ttias.be/iphones-field-test-debug-screen-dial-300...


It doesn't allow you to replace the signal strength indicator anymore, unfortunately (you have to check the strength yourself). Although it now supports dark mode!


If the boy who cried wolf was fined by the townsfolk, he'd be incentivized sooner to stop, and they'd still be motivated to turn up. This doesn't work for impecunious boys, who under this theory should be left to the wolves.


Couldn't you have tested a real number first, and if the target phone rang, then you knew you goofed?

Although obviously testing an emergency number requires no SIM cards...


I've heard similar stories at my old job, except with military radios. Needless to say the other end of the line was very unhappy about interference :)


I can't believe you had to pay a fine to comply with the government's own laws. No reasonable person would expect an operation to make no mistakes here.

How big were the fines? Were they ever challenged in court?


Part of 'complying with the governments own laws' is not making bogus calls. He said himself it happened more than once a month. There's a real cost to dispatching those fire trucks.


The fine is pretty standard practice to discourage repeated nuisance calls. Resources are not infinite and if time is spent on a nuisance call when a real call is delayed, you end up with avoidable injuries and even deaths.




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