Unable to set fd and Unable to clear audiomode on fd


Platform configuration:
Ubuntu 12.04.5 LTS
Asterisk ver 11.25
chan_ss7 version 2.3.11
4 x Digium TE820 (5th Gen)

We are getting warnings below in asterisk messages:

WARNING[20001][C-0000c183] transport.c: Unable to set fd 988 to audiomode
WARNING[20001][C-0000c183] transport.c: Unable to clear audiomode on fd 988

At the beginning this issue raised only on 2 CICs, after there started to be more.
We tried to block locally and remotely affected CICs but were getting same warning

Can anyone advise what could be the problem?

Issue solved after we disabled CRC4 on both ends on all CICs, including the one with signalling link

The strange thing is that with CRC4 enabled on both ends we had noises on about 5% of incoming/outgoing calls also audio mode issue in logs.