asterisk users - May 2004 - Zap callwaiting hookflash idiosyncracy/flaw?

Don't know what else to call this.  Googling and some time on the IRC 
channel haven't gotten me anywhere.

Here's the sitch, which is a bit complicated but is something my 
customers are in fact encountering on an everyday basis:

1. Bob is on a Zap channel talking through the PSTN to Carol.  Both have 
the misfortune, like so many of us, of having LECs who do not offer 
disconnect supervision.

2. While that conversation is going on, Ted calls in on another line and 
selects the ACD option for Bob, and Bob sees Ted's CLID on his phone and 
hears the CW tones.

3. Bob wants to hang up his call with Carol to talk to Ted.

***  Now the possible scenarios, and their apparent resolutions ***

A. Bob hookflashes and takes the call from Ted.  BUT NOW CAROL'S PHONE 
IS STUCK OFFHOOK "LISTENING" TO MUSIC ON HOLD FROM THE THREE-WAY CALL 
CAUSED BY THE HOOKFLASH.  That surely isn't what we want. . . .

B. Bob hangs up for longer than a hookflash period.  Picks up the phone 
and gets a fresh dialtone. But now there seems to be no connection 
between his phone and the incoming call; Ted hears continuous ringing, 
and then gets voicemail.

Bob really wants to be able to take the call from Ted, but Brian can't 
figure out how to configure Bob's dialplan to do it!!

Someone suggested shutting off 3-way calling, but that feature seems to 
be a nice one that everyone makes a lot of use of.

Thanks in advance.

B.