Hi, Excerpts from DOREEN ssssss's message of Fri Oct 26 11:24:37 +0200 2012: SIMtrace currently does not really support class C (1.8V), but it still can sniff the communication even if the phone and card prefer class C. This is done by forcing the communication to use class B (3.0V) because the SIM card is powered using the SIMtrace power supply, which provides 3.3V. I wanted to support all 3 classes (and even more) on SIMtrace 2 which I started 1 year ago, but did not continue since there was no need, nor time. I could send you the current schematic, but it's quite old (and not finished). Because there will be other features there will be quite some changes. As you wish. kevin