ICC is 3G, ME, BSS, VLR/SGSN and HLR/AuC are 2G. The situation is actually very similar to scenario C', but here the 2G HLR/AuC is delivering the necessary 2G triplets directly.
This mixed network environment requires the virtual 2G mode in the USIM, indicated by service no. 38. As a 2G BSS is involved, service no. 27 is also necessary. If the USIM does not support services no. 27 and no. 38, network access is not possible.