Andrei, you have a 50/50 chance of getting it right even if just guessing (providing you know RJ48C is 1-2 4-5)
Normally 1-2 are your recv from network (telco) and 4-5 are your send to network (telco). According to the Contivity documentation your connection is standard BUT they do mention a crossover - and sometimes that happens - like if your connecting Device to Device or telco to telco. The pairs are NOT polarity sensitive but the transmit and recv pairs are. Page 42 in the nortel spec for this card says it all. Also the 4 LED's on the card give a really good indication of where a problem might be (or not if the bottom right GREEN LED is lit).
Cheers,
bb