put https://api.keeptruckin.com/freight_visibility/subscribe/
In Step 3, your POST to this endpoint created a unique tracking subscription ID, which you can find in the response payload. You can now pass in this tracking_subscription_id to modify the subscription start and end time if you need to adjust the pickup or dropoff time for the load. Note that the new start_time can only be earlier than the original, and the new end_time can only be later than the original.
Learn more
Read our reference documentation about the Subscribe endpoint for details.