asterisk users - Oct 2005 - chan_zap.c: Ring/Off-hook in strange state 6 on channel 1

Asterisk version: 1.2.0-beta1 -OR- CVS HEAD
Hardware: Generic X100P clone connected to Panasonic KX-TA624-5 
extension port

The problem happens IF AND ONLY IF:
- the Panasonic is set to use double rings
- the X100P is set to answer immediately (I'm using DISA here)

It does not happen consistently; sometimes Asterisk behaves normally. 
When the "strange state" happens, DISA usually won't respond to
dialing.

I've tried it with busy and call progress detection on and off, and it 
makes no difference.

I have two workarounds, either of which will work:
- Insert a one-second wait before answering with DISA
- Set the Panasonic to send single rings instead of double

It seems that what's going on here is that the FXO port picks up the 
line after the first half of the double ring, just as the second half 
comes in, and Asterisk gets confused because the ring hasn't been fully 
tripped. I don't yet understand enough about the guts of chan_zap.c to 
propose a fix, though.

On an unrelated note, I've found that the clone boards need to have both 
Tx and Rx gain set to -1.5 to prevent echo problems on a Panasonic 
extension port.