asterisk users - Nov 2004 - my asterisk drops connection when remote side puts me on hold?

I've got a TDM100P card with a fxo and fxs module in the US.  I'm
using kewlstart for all ports.  I've noticed that when I make
a call out from an analog phone out the POTS line that if after
talking to the party I called (in this case the phone company itself)
they put me on hold asterisk disconnects the call immediatly.

I've looked around the web pages, but can't figure out what might be
causing this and how to fix it - can anyone give me a clue?

Thanks
Steve Prior