How to customize the content of the SMS notification in OTM?

Summary:

Client wants to send SMS to the customer once the Sales order (EBS) is out for delivery. In OTM we are storing EBS Sales order number in a refnum. how can we get the sales order number to the SMS notification. end user will not know the shipment gid or order release ID . they can identify by the EBS order number,. thank you

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