On a PRI line, I see "yellow alert", what does that mean exactly? Every 3 seconds, an alarm occurs.

Yellow Alarm Active on Trunk
When a yellow alarm is reported on a T1/PRI trunk, the following is displayed: Yellow Alarm A yellow alarm indicates a transmission problem.

www.twitter.com/tem1985
APSS/ACIS/ACSS-SME
not arrogant, just succinct.

Also yellow alarms are indicating a fault with the providers equipment, not the system

RED ALARM indicates corruption, loss of signal or inability to frame reliably.  Essentially this means that the local equipment cannot properly see the far end.  In this case the local system will transmit a yellow alarm while in a red alarm state.

YELLOW ALARM indicates that the system has been instructed by the far end that there is an issue with communication.  If the issue were local the alarm state would be RED but because a yellow alarm must be received.  Also it is not possible to have both a red and yellow alarm state on the same piece of equipment in that you cannot receive the instruction to enter yellow state if you are in a red state.

BLUE ALARM indicates that there is no communication on the path so the equipment will transmit all 1s in the framing time slots to maintain the signal.  When one end is in blue alarm the other end will be in a red alarm and as a result the end in a red alarm will transmit a request for the other end to enter a yellow alarm.

 

Kyle Holladay / IPOfficeHelp.com
ACSS/ACIS/APSS Avaya SME Communications
APDS Avaya Data
MCP/MCTS Exchange 2007/2010
Adtran ATSA, Aruba ACMA

"Thinking is the hardest work there is, which is the probable reason why so few engage in it." - Henry Ford

As I said, it's  not a local issue it's the providers equipment

Yes but it helps to know that a yellow alarm is present because it was requested by the far end equipment so when you call the provider you can say "we have a yellow alarm because your equipment told us to" LOL

Kyle Holladay / IPOfficeHelp.com
ACSS/ACIS/APSS Avaya SME Communications
APDS Avaya Data
MCP/MCTS Exchange 2007/2010
Adtran ATSA, Aruba ACMA

"Thinking is the hardest work there is, which is the probable reason why so few engage in it." - Henry Ford

I put the synchronous clock from the BRI to PRI. Now there are no more yellow alarms.

That makes more sense to me.
I always set a pri as sync master when there are multiple trunks.
But it is good that it is solved.

BAZINGA!

I'm not insane, my mother had me tested!

Well, 4x ISDN BRI to SIP Provider "A" and 1 x PRI to SIP Provider "B". Both units are Patton SmartNode.

Why not sip trunks instead of using these Patton's?
 

BAZINGA!

I'm not insane, my mother had me tested!

"A" is the Austrian provider UPC, they do not have the trunk managed by the IPO. Stupid and even more stupid!