Error on chan_h323(During asterisk startup)

I have successfully intsalled the asterisk and the h323 modules. But while I about the start asterisk with asterisk -vvvvgc command it prompted some errors. Below are parts of the error messages that I had encountered. Please help me on this one. Thanks

[] => (Inter Asterisk eXchange (Ver 2))
[] => (Agent Proxy Channel)
[] => (The NuFone Network’s Open H.323 Channel Driver)
== Creating H.323 Endpoint
ERROR: Could not open H.323 listener port on 1720
Jul 7 09:46:10 ERROR[3255]: chan_h323.c:2366 load_module: Unable to create H323 listener.
Jul 7 09:46:10 WARNING[3255]: loader.c:414 __load_resource: load_module failed, returning -1
Segmentation fault (core dumped)


err … lib versions ? debug logs ? errors during compilation ? h323.conf ?

Could not open H.323 listener port on 1720

You need to make sure the port 1720 is open and not used
by another process.