Investigate "Bad signalling message" error
Sometimes after BTS (observed with osmo-bts-sysmo at least) connects to BSC there's error message:
<001e> input/ipaccess.c:283 Bad signalling message, sign_link returned error: Operation not permitted.
It's originated from libosmo-abis src/input/ipaccess.c:282
It doesn't seem to affect operation (both calls and gprs works nevertheless) but it's still worth checking what's causing it (and fixing spelling of "signaling").