My experience with the Freerunner

Greg Bonett greg at bonett.org
Tue May 27 18:02:00 CEST 2008


Would there be a problem with doing two (or more) calls in series and just
adding up the time of each call?  I would be impressed if the battery
survived through two near four hour calls.  Just be sure to start the
second call shortly after the first one finishes.


>
> On Tue, May 27, 2008 5:27 am, ian douglas wrote:
>> ian douglas wrote:
>>
>> Since the call ended about the same amount of time as my test last night
>> (236 minutes vs 234 minutes), I'm curious if either AT&T or TMobile
>> simply kill a phone call just shy of 4 hours of talk time to free up
>> their network.
>
> That sounds likely.
>
> With GSM the cost of a call is only calculated once the call completes, if
> there is no limit on the length of call, someone who steals a GSM phone,
> can keep a call going for several days, and the network only finds out
> when they hang up. If the call is to an expensive international
> destination ($2 per minute) The cost to the network could be high. Because
> of this most networks limit the length of calls.
>
> The details of the scam are described in chapter 17 of "Security
> Engineering" by Ross Anderson. You can download a PDF copy from this page:
>
> http://www.cl.cam.ac.uk/~rja14/book.html
>
> Back to your test, As far as I know there is no limit on the length of
> calls from landlines, so one solution would be to call the Freerunner from
> an landline.
>
> The other option would be to do what phone manufacturers do, which is to
> measure the current drain from the battery, and calculate the talk time
> from the battery capacity. Don't forget to be unreasonably optimistic
> about signal strength, and battery life. :-)
>
> --
> David Pottage
>
> Error compiling committee.c To many arguments to function.
>
>
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