Re: [Asterisk-Users] W&M Wink timings for Nortel

Sat, 19 Feb 2005 08:47:30 -0800 

        E&M is analogue, not digital...


 



Not true.   You can have E&M signaling on a T1
CAS interface.   Likewise T1 CAS interfaces can also be setup for FXS
and FXO signaling.   This is just how the robbed bits
communicate.   With E&M wink before a remote switch sends a call
to a local switch it send a very 0/1 transition on the A bit.  When the
local switch sees the wink it is supposed to respond with its own “wink”
back at the originating switch.  Then and only then is the call sent over
and DTMF is sent inband.  On T1s this wink parameter is tunable and you
should be able to set the wink pulse width and timing.   



 



I suspect that the Digium card either isn’t answering
the wink or is sending it with the incorrect timing or pulse width.   The
best way to troubleshoot this is to place a T1 analyzer on the line such as Fireberd.
  They can be rented for a day from Electrorent.  



 



Also, you may want to see if you can setup the T1 span for
immediate-start.   This would mitigate any wink problems.



 



For more info on how T1s work with voice see:



 



http://www.cisco.com/en/US/tech/tk652/tk653/technologies_tech_note09186a00800e2560.shtml



 



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