Is there any possibility to place a SIP/PSTN call with out having registered from a mobile/desktop browser ,just click to call something like that - No registration
if yes , how ? and
if yes, is there any possibility to track it and getting user information like log information (Time of call + location + duration )
Yes, depending on the server configuration and in the real use case you want.
The registration in SIP is a request to inform the server that "this" user using "this" application will be available on "this" IP and "this" port during the following X seconds with "this" capabilities. Using that information, the server can redirect SIP requests that are for the registered user.
Without that information, how can your server contact an aplication, without knowing where it is reachable, and without knowing who the user is?
But, if you only want a call from the clients to a known service, (like a click to call), SIP also allows it if you just send an INVITE with the SDP information. You will need to create an identity anyway, even if it's a random one and use it in the requests. Your SIP server will have to be configured to accept requests from unknown random identities without registration.
If you want to use WebRTC, that is one of the possible use cases but you still have to translate anywhere the requests to SIP, or go with one of the possible opensource solutions. Here's an example.
After having the calls running on your server, recording statistics from calls it's just a simple thing to do. You have a lot to worry before that :)
