[Asterisk-Users] How to fix a Blue Alarm?? Line Noise?

[Bruce Ferrell]

Peter Svensson wrote:
> On Fri, 12 Aug 2005, Bruce Ferrell wrote:
> 
> 
>>Hardware, possible.  Unlikely to be cabling.  It's usually a timing setting.
> 
> 
> The blue alarm is really a very specific alarm condition normally. It 
> cannot quite see how it can be generated accidentally. Something along the 
> path from the TE110P transmitter to the decoder in the pbx generates a 
> AIS condition on the line. Theoretically a repeater or converter 
> withing the pbx could generate the AIS condition on the line.
> 
> Another option is that the pbx uses the term "blue alarm" for something 
> other than the normal AIS signal on a T1. 
> 
> Disturbances and frame slips would normally generate a local OOF 
> condition, eventually triggering a local red alarm and sending of yellow 
> alarm indication to the remote side.
> 
> Peter
> 
Well Peter, yo gone and done it... Ya made me go look it up :)

A red alarm means "I don't see any signal".  A blue alarm means "I see a 
signal and something downstream (repeater etc) is saying they don't see 
a signal".

I used this as my reference:
http://www.fratec.com/FAQ/NFO/NFO_WAN_009.HTML


Slips sometimes cause an LOF condition, sometimes they don't.  At least 
when I worked NorTel DMS250 switches back in the 80's that's the way it was.

Thanks for making me stretch my mind!