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SIM cards - physical differences

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Old January 21st 12, 02:17 PM
Junior Member
First recorded activity by MobileForum: Jan 2012
Posts: 4
Default SIM cards - physical differences

I am having problems with SIM cards that have physically different contact configurations from one another generating “Invalid SIM card” messages in a Brand New, SIM Free, 2G only N388 Watch/Phone purchased from the Far East.

I have attached a photo of 4 SIM cards, the RED one is from Vodafone, the Black one is from Orange, the Blue one from Tesco and the White one from GifGaf.

[Tesco & GifGaf are both ‘Virtual’ Networks utilising the O2 Network].

Note - the Black & Red SIM cards on the right are ‘upside down’, i.e. rotated through 180 degrees – note the corner cut – I pictured them like this so that the metal areas appear adjacent.

Both the Red (Vodafone) and Black (Orange) cards work OK in the N388 Watch/Phone BUT the Blue (Tesco) and White (GifGaf) cards do not, generating an “Invalid SIM card” message.

ALL of the SIM cards work in ALL my other mobile phones!

You can see that the size of the metal area containing the contacts is different between the Blue & White SIMs and Black & Red SIMs, the smaller Blue & White cards having two columns of three contacts either side separated by a central vertical area (i.e. a total of six contacts) whilst the larger Red & Black cards have two columns of four contacts each side separated by a central vertical area BUT in fact the top right contact is NOT separated from the central vertical centre section so there are in fact seven possible contacts.

This means that when the SIM cards are put into the Watch/Phone which has two columns of three contacts, in the case of the Blue & White SIM cards each contact in the phone connects to a different discrete contact on the card, i.e. six connections are made BUT in the case of the Red & Black SIM cards one of the contacts in the phone is, in effect, connecting to the centre section, i.e. only five of the phone contacts are making connections – you can see the scratches/marks made on the SIM cards by the phone contacts as the SIM cards are slid in to place. Two of the possible contacts on the larger Red & Black SIM cards (the bottom two in the picture) are not provided with contacts in the phone and are therefore never used.

I also have an ASDA mobile SIM card {ASDA is another Virtual network but operating on the Vodafone Network} which is of the larger Red & Black SIM card type and it also works OK in the Watch/Phone.

To summarise, the SIM card types that only provide five usable contacts (Red & Black) work OK but the ones that provide six (Blue & White) generate the “Invalid SIM card” message on the Watch/Phone.

Can anyone explain this situation – the reasons for the different numbers of contacts on the SIM cards and their purposes and why this may be causing a problem in the Watch/Phone but not in any other phone.
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