CTI interaction

A customer needs to make its own enterprise management software to interact with FreePbx in order to allow each operator terminal to open customer worksheet based on caller ID and extension destination.
Their programmers say "we can do it, just tell us how we can collect data from PBX and what data we expect ".
Probably more a exquisite Asterisk question, but where I can find documents about CTI/Tapi/etc to start from with asterisk ?

Thank you very much.

I would suggest you take a look at iSymphony, it has hooks that allows you to send data to both URL’s and programs.

Ok I’ll take a look

I tried to work around Asterisk Manager Interface (AMI)
Just a telnet on port 5038, right autentication and you can read/write a lot of things as per Asterisk Manager User settings/permissions.
Could it be a safe way to proceed ??