Simple Free Helpdesk And Bug Tracker

From the point of view of your customer, it is a good idea to have a single login page for all of your applications including Sancho. If you want a centralised login then you do not need to maintain users list in Sancho. When a customer successfully logs in to your application, just add a single line.
$_SESSION['Sancho'] =
    sprintf('%s;%s;%d', 'username', 'company', 'access_level');
When the customer goes to help desk, Sancho will read the $_SESSION['Sancho'] and let the user in with privileges stated in access_level.

sprintf Parameters:

username: the user name under which your customer logs in
company: optional
access_level: one of the following
0 = Guest
1 = User
2 = Tech support
9 = Admin