Sending Multi-Channel Fallback Requests

The Conversation API allows enterprises to send fallback message requests — for example, if RCS fails, attempt WhatsApp; if WhatsApp also fails, attempt SMS. Enterprises can choose any two or all three channels together in any order.

note

The enterprise must be onboarded for all channels before sending a fallback request.

RCS → SMS Fallback

If RCS delivery fails (DLR received from channel), SMS is triggered. DLRs for both messages are pushed to the enterprise webhook URL.

SMS Parameter Reference

#	Parameter	Description	Required
1	userid	User ID provided by Sinch India	M
2	pass	Password for authentication	M
3	appid	Application ID	M
4	subappid	Subdivision app ID	O
5	msgid	Unique ID per request (generated by enterprise)	M
6	msisdn	Mobile number(s) — comma separated for multiple	M
7	from	Sender ID	M
8	contenttype	1 for text SMS	M
9	selfid	Set to true	M
10	text	Message text	M
11	dpi	DLT principal entity ID	O
12	dtm	DLT template ID	O
13	tc	Template category: 1=Transactional, 2=Promotional, 3=Service Implicit, 4=Service Explicit	O
14	language	Regional language code	O
15	shorten	URL shortening flag (0=disable, 1=enable)	O

M = Mandatory, O = Optional

Sample RCS-SMS Fallback Request

{
  "app_id": "01H0MFFJFX0YAWYA5XG4D3MRTA",
  "recipient": {
    "identified_by": {
      "channel_identities": [
        { "channel": "RCS", "identity": "919876543210" },
        { "channel": "SMS", "identity": "919876543210" }
      ]
    }
  },
  "message": {
    "explicit_channel_message": {
      "SMS": "{\"userId\":\"sindsasms\",\"pass\":\"sincdjh_5\",\"from\":\"ACLTST\",\"selfid\":\"true\",\"contenttype\":\"1\",\"to\":\"919876543210\",\"text\":\"Hi Shubham greetings from ACL.\",\"alert\":\"1\"}"
    },
    "template_message": {
      "channel_template": {
        "RCS": {
          "template_id": "test_rich_carousel",
          "language_code": "en",
          "parameters": { "amount": "INR 500", "discount": "20%" }
        }
      }
    }
  },
  "channel_priority_order": ["RCS", "SMS"]
}

API Response

A successful request returns HTTP 200 with the following structure:

{
  "message_id": "01H4ZNS6KDC7YDBXN95CWRHPBS",
  "accepted_time": "2023-07-10T10:33:00.781Z"
}

The message_id is the unique identifier used in DLR callbacks.