Asterisk call making

I try to make call using asterisk server and two clients. i got the call routed through the server but status of sip user is unmonitored.
Please tell the procedure for monitoring the clients.
Also tell where exactly does the client information gets stored in the asterisk server.

Unmonitored is for when you register out. Regardless I don’t think Asterisk “Monitors” it the way you want it to. How do you want the channels monitored ? You may want to use third party software such as Nagios.

Can we use asterisk as a SIP-H323 gateway?

Yes though in my tests H323 is very unreliable and it caused my test box to core dump up to several times a day.

How to configure asterisk as SIP-H323 gateway?

How you would configure anything else. You have to set up h323 and sip and then set up the calling rules in the dial plan.