@leissner/node-red-smpp

Node-RED nodes for sending and receiving SMS via SMPP, built on top of the smpp npm package.

Nodes

• smpp-config — shared connection/bind configuration (host, credentials, bind mode, TLS). Manages the underlying SMPP session, including automatic reconnect with backoff.
• smpp-out — submits an SMS (submit_sm) to the bound SMSC.
• smpp-in — receives inbound messages and delivery receipts (deliver_sm) from the bound SMSC.

Install

Via the Node-RED editor's Palette Manager, or from the command line in your Node-RED user directory (typically ~/.node-red):

npm install @leissner/node-red-smpp

smpp-config

Holds the connection details for one bound SMPP session, shared by any number of smpp-in/smpp-out nodes. Configure url (e.g. smpp://host:2775, or ssmpp://host:3550 for TLS), system_id, password, and bind_mode (transceiver/transmitter/receiver). Advanced options include addr_ton/addr_npi/address_range (only needed if your SMSC provider tells you to set them), enquire_link interval, connect timeout, and TLS settings for ssmpp://.

The connection is established lazily on deploy (when the first smpp-in/smpp-out node using it starts) and torn down when the last one is removed. On disconnect, it retries with capped exponential backoff (1s → 2s → 5s → 10s → 30s, then holds).

smpp-out

Sends msg.payload as an SMS.

• Destination — set on the node, or leave blank to use msg.destination.
• Source — set on the node, or leave blank to use msg.source.
• Encoding — Auto-detect (default), ASCII (GSM 03.38), LATIN1, or UCS2. Can be overridden per-message with msg.encoding (same values, case-insensitive). If the payload contains characters the chosen encoding can't represent, a warning is logged and the unrepresentable characters are substituted or dropped by the underlying library — switch to auto or UCS2 if you need those characters preserved.
• Message class — optional, under Advanced. 0 marks the message as Flash (most handsets display it immediately without storing it); 1-3 are the less commonly used ME/SIM/TE-specific classes. Can be overridden per-message with msg.class (0-3). Only supported with GSM 7-bit or UCS2 — combined with LATIN1, a warning is logged and the message is sent without a class marking. With auto encoding, GSM 7-bit or UCS2 is chosen automatically based on the message content, same as normal auto-detection.
• msg.payload that isn't already a string or Buffer is converted: plain objects are JSON-stringified, other types are coerced with String().
• On success, msg.payload is replaced with the SMSC's message_id, and the full response PDU is attached at msg.smpp_response.

Note on LATIN1: only data_coding 0x00 (GSM 7-bit) and 0x08 (UCS2) are universally honored by SMSCs and handsets. LATIN1 (0x03) is valid per the SMPP spec but has been observed to be silently misinterpreted as GSM 7-bit by some SMSCs — test against your specific SMSC before relying on it for anything outside the base GSM alphabet.

smpp-in

Emits a message for each inbound deliver_sm PDU. Configure whether to receive all messages, MO (mobile-originated) only, or delivery receipts only, and whether delivery receipt text is parsed into a structured msg.payload (id, sub, dlvrd, submit_date, done_date, stat, err, text) or left as raw text.

Auto-acknowledges each received PDU by default (required by the SMPP spec) — only disable this if your flow explicitly sends the response itself via msg.smpp_pdu.response().

Examples

Three example flows are included — in the Node-RED editor, use Import → Examples → node-red-smpp (or @leissner/node-red-smpp, depending on your Node-RED version):

• Send SMS — the minimal flow: an inject node with a test message and destination number, wired to smpp-out, with a debug node showing the returned message_id.
• Send flash SMS — the same shape, but the inject node also sets msg.class = 0, demonstrating Flash SMS.
• Receive SMS — smpp-in wired to a switch node that splits inbound traffic on msg.smpp_is_delivery_receipt, routing mobile-originated messages and (parsed) delivery receipts to separate debug nodes.

All examples ship with a placeholder smpp-config node (smpp://your-smsc-host:2775, system_id: your_system_id) — edit it with your real SMSC details and set a password after importing, before deploying.

Development

The pure encoding/payload logic used by smpp-out (message class byte math, encoding resolution, payload normalization) lives in lib/message-encoding.js and has a Mocha test suite:

npm install
npm test          # run tests
npm run coverage  # run tests with coverage report (coverage/lcov-report/index.html)

The smpp-config/smpp-out/smpp-in nodes themselves depend on a live SMPP session and Node-RED's runtime, and are tested manually/interactively against a real SMSC rather than with automated tests.

License

MIT