Restricting Support to the Installed Base
If you want to use the installed base as a validation database, set Items in Installed Base to Yes. This prevents the creation of call quotes and calls referencing an item not in the installed base. When set to No, only a warning displays in these functions. When you take calls for items not in the installed base, the installed base record is created before you record activity or when you close the call.
If you do not know your end users until they call the support department, you should set this field to No.
A similar field also exists in Contract Control (11.5.24), which determines how items added to contract and contract quotes are validated. The contract value defaults from Service Management Control. The two fields support a flexible approach to managing the installed base. For example, you can set the field in Service Management Control to No so that you can take calls for any item. Then set the field in Contract Control to Yes so you provide coverage for items in the installed base only.
You can define any combination of Yes and No values for the two Items in Installed Base fields. However, setting Items in Installed Base to Yes at the system level and No at the contract level can create problems if you do not ensure that covered items are added to the installed base later. Otherwise, you will not be able to create a call for an end user with valid contract coverage.