To attach a device template in Cisco SD-WAN, you must issue a POST call to initiate the attach action. This is the first step in the process. After initiating the attach action, you need to monitor the status of the action. For this, you issue a “monitor device action status” GET API request with the process ID. The process ID is used to track the status of the attach action until it is completed.

References := Automating Cisco Enterprise Solutions Official Cert Guide, SD-WAN