Hi Agus
Please follow as mentioned below if you are sing
Availability Check Using External Systems:
You can also use SAP-external software for the availability check. You connect an external system with SAP CRM to execute an availability check or to get availability information.
You can find more information under availability check and availability information.
Integration
A series of Business Add-Ins (BAdIs) is available for the connection of an external system to SAP CRM for the availability check. The BAdIs are located in the Implementation Guide (IMG) for Customer Relationship Management under Basic Functions Availability Check Availability Check / Info Using External ATP System.
You need to implement the BAdIs that contain the necessary logic to connect the required external system and to provide it with the necessary input data.
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If you wanna ATP information from ECC pls follow mentioned below one:
Availability Check Using SAP ERP
If you perform material requirements planning in SAP ERP, you can perform an availability check (ATP check) using SAP ERP in the business transaction in SAP CRM.
Prerequisites
In SAP ERP
In SAP ERP, you must activate the business transaction events (BTEs) for the Availability Check Using SAP ERP. To set this flag in SAP ERP, do the following:
Enter transaction FIBF.
Choose Settings Identification SAP Applications .
Enable the CRMATP application.
In SAP ERP, the material must not be relevant for the availability check with SAP APO.
In SAP CRM
In SAP CRM, you change the setting to availability check using SAP ERP in Customizing for SAP Customer Relationship Management under Basic Functions Availability Check Availability Check Using SAP ECC Define Middleware Parameters: Availability Check Using SAP ECC .
For information about settings for availability check in SAP ERP, see Customizing for SAP ERP under Sales and Distribution Basic Functions Availability Check and Transfer of Requirements .
Regards
Adi.