ESME_RX_T_APPN in SMPP

What is ESME_RX_T_APPN?

ESME_RX_T_APPN (Error Code: 0x00000064) is an SMPP error indicating that a response from the SMSC was not received within the expected time (response timeout).

Possible Causes

  • The SMSC did not respond to a request within the timeout period.
  • Network latency or connectivity issues between the ESME and SMSC.
  • The SMSC is overloaded or experiencing delays in processing requests.
  • Incorrect configuration of timeout settings on the ESME side.

When Does It Happen?

This error occurs when the ESME sends an SMPP request (such as submit_sm, deliver_sm, or bind_transceiver) but does not receive a response from the SMSC within the configured timeout period.

Example SMPP PDU Transaction

Request PDU (submit_sm) Sent by ESME

0000003F (Length)
00000004 (Command ID for submit_sm)
00000000 (Command Status)
00000001 (Sequence Number)
00 (Service Type)
01 (Source Address TON - International)
01 (Source Address NPI - ISDN)
31323334 00 (Source Address: "1234")
01 (Destination Address TON - International)
01 (Destination Address NPI - ISDN)
39383736 00 (Destination Address: "9876")
00 (ESM Class)
00 (Protocol ID)
00 (Priority Flag)
00000000 (Schedule Delivery Time - Not Set)
00000000 (Validity Period - Not Set)
00 (Replace If Present Flag)
00 (Sm Default Msg ID)
0005 (Message Length)
48656C6C 6F (Message: "Hello")

Response PDU Not Received

The ESME waits for the submit_sm_resp PDU, but no response is received within the configured timeout period, leading to an ESME_RX_T_APPN error.

How to Solve It?

  • Increase the response timeout setting in the ESME configuration.
  • Check network connectivity between the ESME and SMSC.
  • Ensure the SMSC is not overloaded or experiencing delays.
  • Monitor SMPP logs to identify patterns of delayed or missing responses.
  • Verify that the SMSC is correctly processing requests and sending timely responses.

If the issue persists, contact the SMSC provider to diagnose potential server-side delays.

More information