CRC of Preferred Roaming List problem

I have a problem with the crc calculation for the preferred roaming list. Here is a roaming list from a motorola phone

Roaming List NAM 0: 00 31 30 39 00 02 40 03 10 51 c8 49 8c 6b b9 6a b0 74 d8 e1 b8 6e 14 a3 70 89 94 a3 02 5d 63 47 84 57 41 15 e0 0c 08 22 bc 81 02 2b 9c 0a 06 98 dd

The last two bytes are the 16 bit CRC-ccitt result for the message ahead. According to the protocol TIA-EIA-IS683A , the crc calcuation is described as follows:

Page 3-43 of IS683A

) the 16 bit preferred roaming list crc field PR_LIST_CRC is calculated on all bits of the PRL excluding the bits of the PR_LIST_CRC field itself. The generator polynomial for this CRC is g(x) = x^16+x^12+x^5 +

1 ................ using the logic shown in figure 2.2.1-2 .............. initially, all shift register elements are set to logical one and the switches are set in the position A. the register is clocked with each preferred roaming list bit as an input,from the most significant bit of the PR_LIST_SIZE field through the least significant bit of the reserved field. the switches are set in the position B and the register is clocked an additional 16 times. the 16 additional output bits constitute the CRC.

value 0xffff, am I correct ?

After I programmed like the protocol , I found the crc result is 0x6722 instead of 0x89dd. Also I tested on the website

which gave me the same result ( which means I am correct ? )

Now I am wondering whether it is possible they use a different algorithm to calculate the CRC of the preferred roaming list ? And I am wondering whether it matters if I use the protocol algorithm not their algorithm.