[asterisk-dev] On hook reversals

Mike Jagdis mjagdis at eris-associates.co.uk
Tue Jun 5 08:52:06 MST 2007

On Tue, Jun 05, 2007 at 07:55:49AM +0800, Steve Underwood wrote:
> In the Zaptel code, the ZT_SETREVERSAL command tries to prevent 
> reversals from being set while the loop is open. This test seems to fail 
> under some circumstances, as I have had the driver in a state where 
> reversals work just fine while the loop is open. I'm not clear what gets 
> the driver in that state. However, my actual problem is I really need to 
> generate reversals when the loop is open. Some of the caller ID specs 
> require this. Can anyone tell me why these reversals are prevented, when 
> it seems the hardware is quite happy to perform an on-hook reversal?

You mean ZT_SETPOLARITY? You have to do a ZT_ONHOOKTRANSFER as well if
you want reverse polarity transfer on-hook (or go off hook if you want
loop). If the SI chipset isn't either off hook or in the on hook
transfer state polarity has no meaning. (I think it actually sleeps
in some "low power" state)


Mike Jagdis                        Web: http://www.eris-associates.co.uk
Eris Associates Limited            Tel: +44 7780 608 368
Reading, England                   Fax: +44 118 926 6974

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