Posted by mrvanx
Hey people, ive just recently purchased a HTC TyTN and currently use (obviously) a 2.5g sim card in my P900, what do i need to do to upgrade my tarriff to 3G?? Im on O2-UKs Online 100 off peak tarriff, in my pack it did show prices for video calls and data etc... but would i need to call O2 for a USim to enable 3G on my contract????
And to show the point of this thread....what is the difference between my current Sim and a USim????
Posted by sosojerk
Just call o2 and find out.
Posted by goldenface
You will need a 3G sim from O2. The difference, physically they look the same its just that one is compatible with UMTS
Posted by kalleboo
SIM contain the required cryptography keys for a GSM network.
USIM contain the required cryptography keys for a UMTS (3G) network.
Posted by Kimi
Physically those SIMs are exactly the same. Also the software is the same. And the crypto-keys can be updated by the operators over-the-air if they want to.
I have a GMS SIM from 1998 (very old) and it is working perfectly well with all 3G UMTS services (swisscom). So the SIM change is just something that the operator forces you to do and if it costs something it is just to make money.
Posted by kalleboo
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The software isn't exactly the same, some more obvious differences is that the phone book storage on USIM is much more advanced.
The encryption is also stronger on USIM:
Quoth Wikipedia: The development of UMTS introduces an optional USIM, that uses a longer authentication key to give greater security, as well as mutually authenticating the network and the user - whereas GSM only authenticated the user to the network (and not vice versa).
So if your network allows the use of an old SIM on a UMTS network, they've probably opted to allow for classic (weaker) GSM encryption on UMTS.
Operators that charge for a USIM are just greedy, mine sure didn't.
Posted by goldenface
Orange UK charged me?
O2 didn't, neither did T-Mobile?
Posted by mrvanx
So its probably better to have a Usim rather than keeping my current one then??
Posted by Kimi
kalleboo,
thanks for making this clear. So maybe I should ask for a USIM as well (if they have any). The more secure the better.