[asterisk-dev] remote call supervision

[Bob]

Currently there is no difference between loop start and kewl start in the
receive direction in zaptel. In the transmit direction there is a provision
for removing battery for ZT_KEWL_TIME when the near end hangs up. There is a
recent hack patch that has made its way into the trunk branches that alarm
the span or channel when there is no battery. This patch is OK, but it
shouldn't be used to detect far end disconnect. 

IMHO, the proper way to handle the far end disconnect, and the battery alarm
is to implement an RX_KEWL state into zaptel instead of hoping that the DAA
interface will die off and report when it's battery is pulled away from the
far end. Some don't die. Some take longer to use the charge already stored.

All of our equipment will hang up on its own when battery is removed for a
specified period. We use the standard 0xf on the rx abcd bits to represent
this, and everything works fine. The problem with zaptel is that it is
waiting for its own fxo circuit to hang up instead of detecting the lack of
battery and doing so itself. 

This requires modification to zaptel, and chan_zap. I'm asking that someone
at the big D, just go ahead and do this instead of messing with all the
small patches and headaches.

Bob