1.  The customer or the end user logs a call through any
tool or by mail 
tools are:
(RADIX).
Remedy
Service Desk (SD4)
Perigreen 
lotus notes

 2.  Each one of the support team is a part of support group. 
 3. Whenever a customer logs a call he /she have to mention
to which work group (by name). 
 4. Once the calls came to the work group the support
consultant or the team needs to send an IR (Initial
Response) to the user depending upon the priority of the
calls. (Top, High, Med, Low, None) 
 5. Then the error is fixed, debugged by the support
consultant or the team. Then after testing properly by
generating TR (Transport Request through the basis admin) 
 6. Then it is informed to the end user/customer/super user
about the changes which have moved to the production server
by CTS process. 

These are the process.  In summary, what I understand is
that if any configuration or customization is required to
solve the issue, then the consultant have to work on DEV
Client, then the end user will test it in the QA client and
after approval the BASIS consultant has to transport it to
the PRODUCTION client.

A work item should be classified as Production Support based
upon the turn around time to complete it. For example, if a
bug is critical enough to stop the production server, it can
be taken up as a Production Support to resolve it on
immediate basis. Another example of product support type of
work are following:

-Configuration and customization
-User Acceptance Testing
-Database backup
-Clearing of all the data in database
-Changing of name, title, text etc in live working applications
and so on...

Basically if the bug fixing is not so critical and if it can
wait and takes a long time to fix and test it, it should be
ideally classified under Bug Fixing type of work request
instead of Production Support.