As per the new regulation that has been rolled out in India, by the Telecom governing body TRAI, it is now mandatory for all domestic/Indian based companies that intend on sending SMSes to their end customers, to register the Sender IDs as well as the message templates that they intend on using.
So, if messages are triggered without a Template ID (either via application or via API) they will fail to deliver to your end customers.
Find out how to register your template now.
You can either add the template IDs to the Kaleyra platform and then continue to send messages via API without changing anything or make modifications in your API by adding the new parameters of Entity ID and Template ID while sending the API request.
Read more on the API changes here.