I need to make a software HDLC simulation on ISDN B channel by capturing the B channel data implemented on standard 51. HDLC data is protected by 16bit CRC.

Can anyone help me with the polynomial. I have checked the standard:
X16+X12+X5+1 and X16+X15+X2+1
but none of them seems to be the right one.

I have captured the data from the B-channel and here are 2 examples of CRC16 on a single byte: (data was sent to ICC by the USB-CAPI modem in extended transparent mode)

01 - gives the CRC16: F1 E1
02 - gives the CRC16: 6A D3

Thank you!

Franc