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ETSI 102 221 mentions the existence of two transmission protocols：T=0 and T=1. But when I tested my 4g USIM card, according to received ATR, I found that it only supports T=0. So I can't test T=1 related code. One of the sayings I found on the Internet is that the current telecommunication service mainly uses T=0.

As the issue describes, is there a USIM card that only supports protocol T=1? I hope that someone with experience in this area can help answer this question, and I would appreciate it.

kkew13
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  • I can't imagine, that a supplier offers a card only capable of the minority protocol (*mainly T=0* seems a drastic understatement). I did not encounter a SIM, which even understood T=1. – guidot Aug 23 '23 at 09:26
  • I changed another usim card, but the situation is still the same. I tried to change to T=1 through pps, but failed. – kkew13 Aug 23 '23 at 14:38
  • Of course,PPS can only select whichever protocol exists in the card, T=1 most likely does not. Perhaps you can give more context about your problem instead of trying to pursue this non-promising path. – guidot Aug 23 '23 at 15:45
  • Thank you very much, yes, I am preparing a usim card reader. I've implemented T=0, but I found that several of my usim cards do not support T=1. I'm thinking whether I should drop the T=1 implementation and just use T=0. – kkew13 Aug 24 '23 at 03:01

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