[asterisk-dev] Loop start vs kewl start for T1 interface

[Justin Killen]

This is a cross-post from the users list, where there was no response - hopefully somebody here has a deeper understanding...


Is there a doc somewhere that explains when to use loop start vs. kewl start in certain situations? I've seen in a lot of posts that most people just say 'use kewl start', but nobody really explains why. It seems that if kewl start should be used 100% of the time then why is there even an option for loop start? After some research, it seems like there are 4 main loop start setup options:

 1.  loop start (classic)
 2.  loop start with battery reversal
 3.  loop start with battery drop (kewl start)
 4.  loop start with tone detection

Am I correct in assuming that when using kewl start that both these things happen?

 1.  If the far end disconnects, the code will look for battery drop
 2.  If the near end disconnects, the code will initiate a battery drop

My question is, if I'm using a T1 channel bank, do these values matter on the T1 interface, or only on the channel bank itself. In other words, do the disconnect supervision signals cross the channel bank and end up in the T1 signal, or does the T1 signal use a different mechanism to signal a disconnect?

Specifically, I'm trying to use an Adtran Total Access 850 with FXO cards, and fairly often I will get phantom calls. I believe this to be a result of a hangup not being detected correctly (I get "Ring/Off-hook in strange state 6 on channel X" messages).

On a side note, Is there some kind of 'learning' tool that I can run that monitors the line and displays these kinds of events during the duration of a call? For instance I could run the tool and then it could guide me through a series of 'I call you, you call me' scenarios and then the tool would tell me what settings to use?


Justin Killen
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