Chancing SIM card without reboot

David Pottage david at
Tue Sep 2 21:48:50 CEST 2008

Fredrik Wendt wrote:
> Hi.
> Just wanted to know if I'd damage the hardware by doing:
> 0. Connect FR to computer using USB cable.
> 1. Turn on FR (FSO-testing), fire up zhone.
> 2. Open FR, remove battery, open SIM pocket, change SIM card, replace
> battery, replace back cover - all while the FR is running off power from
> In Sweden we have three GSM network operators (those with licenses to
> actually put GSM equipment to use) and having to wait 3-4 minutes after
> each SIM change really kills productivity and flow ...
There is a risk that you will damage the SIM card doing that, as it may 
receive power on the data pads before ground and power are connected. On 
consumer phones where the sim card is not under the battery there is 
normally some sort of switch on the SIM card compartment so that the 
phone, or at least the GSM module gets powered down if you attempt to 
remove the SIM card.

On the Freerunner, it would be best if you powered down the GSM module 
before you remove the SIM card. Perhaps in future we can add an applet 
to do that.

You might consider testing if the power gets removed from the SIM card 
pads when the GSM module is off, by probing it with a multimeter, though 
do so at your own risk, as there is a slight chance of damaging your 

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