asterisk users - Feb 2005 - Transfers to engaged extensions

Hi,

I'm using zaptel with three way calling and call transfers with a hookflash.

If I try transfering a call to an extension that is engaged I get an 
engaged tone. This is fine, but how do I get back to the caller?

If I hookflash again I seem to put on a three-way call and the caller 
can hear the beeping. I can press hookflash again but I'd prefer the 
caller to hear only the hold music and then me speaking.

Is this intentional or am I doing something wrong?

Robie.