Write a transient state as an intermediate delivery notification

src/dlr.ts

@@ -131,7 +131,7 @@ export function parseReceipt(message: string): Receipt {
 type MessageType = 'intermediate' | 'other' | 'receipt' | 'unmarked';
 
 /** SMPP 3.4 Appendix B lists every other receipt state as final. */
-const transientStates: MessageState[] = ['ENROUTE', 'SCHEDULED'];
+export const transientStates: MessageState[] = ['ENROUTE', 'SCHEDULED'];
 
 /** Written by the far-end SME, not by the MC reporting on a message we submitted. */
 const smeMessageTypes: number[] = [

src/sms.ts

@@ -5,7 +5,7 @@ import type { Result, VoidResult } from './result.ts';
 import type { Session } from './session.ts';
 import { UnansweredError } from './unanswered-error.ts';
 import { consts } from './defs/constants.ts';
-import { receiptCodes } from './dlr.ts';
+import { receiptCodes, transientStates } from './dlr.ts';
 import { smppDate } from './message.ts';
 import { uuidv7 } from './uuid.ts';
 
@@ -192,7 +192,9 @@ async function sendDlr(
 			cmdName: 'deliver_sm',
 			params: {
 				destination_addr: sms.from,
-				esm_class: consts.ESM_CLASS.MC_DELIVERY_RECEIPT,
+				esm_class: transientStates.includes(status)
+					? consts.ESM_CLASS.INTERMEDIATE_DELIVERY
+					: consts.ESM_CLASS.MC_DELIVERY_RECEIPT,
 				short_message: receiptText(sms, smsId, status),
 				source_addr: sms.to,
 			},