asterisk users - Jun 2006 - EuroISDN and Sangoma Card

Hi List,

Just a little question about a notice from asterisk I don't understand:

Here is what I have as soon as I place a call on a E1 line with an a104D 
Sangoma Card ( asterisk 1.2.9.1 ) :

Jun 26 18:57:24 NOTICE[16489] channel.c: Don't know what to do with 
control frame 15

Does Anyone has a clue of how to get rid of that ?

May it's because I use the HDLC decoding in hardware ?

Thanks in advance for your help !!!

Cheers,

Tristan