Alcatel Unleashed

Hello,i have this problems on my Alcatel:
01/03/23 08:35:33 000001M|001/06/0/000|=4:2085=Access T2, board (1,6) : synchronization stopped
01/03/23 08:35:33 000001M|001/06/0/000|=4:2112=NOS alarm on T2 access
01/03/23 08:35:33 000001M|001/06/0/000|=2:0310=T2 Dlap Released
01/03/23 08:35:53 000001M|001/06/0/000|=4:2080=T2 access is synchronizing on Board (1,6)
01/03/23 08:35:53 000001M|001/06/0/000|=5:2102=T2 access back to normal
01/03/23 08:35:53 000001M|001/06/0/000|=4:2113=T2 lapD not established still trying
01/03/23 08:35:53 000001M|001/06/0/000|=5:0311=T2 Dlap Established

this type of error occurs randomly. Sometimes every 5 minutes sometimes every half hour and I can't figure out what could be causing it. My isp checked the line and found no problems. What could it be about?

Thanks.
Daniele

NOS - signal absent. Some problem with equipment between your PBX and provider.
What error have provider in the same time - NOS, RAI, AIS?

nos =no signal recived your rx is empty pbx should send RAI at least , did you perform a loop test toard provider and vice versa