asterisk users - Mar 2005 - What different between asterisk-oh323 and astersk's chan_h323 ?

Dear ALL:

I find that everybody discuss with asterisk-oh323 instead of chan_h323
of asterisk channels. Why do they choose asterisk-oh323 and not use
the build-in module (chan_h323)? What different between these two
componments?

In my guess, the build-in module should be easy to implement rather
than setup another application(asterisk-oh323) expect some bugs or
failed functions on chan_h323.

Dose anybody tell me how to implement a Asterisk to H323(register to
gatekeeper)?

I want my asterisk(as GW mode) register to GNUGK.

Best Regards 
Charles