One workflow. One outcome: your data.

iridiumDataId: 123456
imei: 300234012345678
sim: 
messageId: 42
dateTime: 2026-10-05T18:30:00.000Z
endTimeOfSession: 2026-10-05T18:30:04.000Z
dataLength: 5
data: 48656c6c6f
satelliteLatitude: 32.7157
satelliteLongitude: -117.1611
satelliteRadiusKm: 12
sessionStatus: COMPLETE

<h2>Telemetry Station Iridium message</h2><table>
<tr><th align="left">iridiumDataId</th><td><code>123456</code></td></tr>
<tr><th align="left">imei</th><td><code>300234012345678</code></td></tr>
<tr><th align="left">sim</th><td><code></code></td></tr>
<tr><th align="left">messageId</th><td><code>42</code></td></tr>
<tr><th align="left">dateTime</th><td><code>2026-10-05T18:30:00.000Z</code></td></tr>
<tr><th align="left">endTimeOfSession</th><td><code>2026-10-05T18:30:04.000Z</code></td></tr>
<tr><th align="left">dataLength</th><td><code>5</code></td></tr>
<tr><th align="left">data</th><td><code>48656c6c6f</code></td></tr>
<tr><th align="left">satelliteLatitude</th><td><code>32.7157</code></td></tr>
<tr><th align="left">satelliteLongitude</th><td><code>-117.1611</code></td></tr>
<tr><th align="left">satelliteRadiusKm</th><td><code>12</code></td></tr>
<tr><th align="left">sessionStatus</th><td><code>COMPLETE</code></td></tr>
</table>

• Prefer the text/plain part. Every field is one line in the form `name: value`, in the same order as the HTTPS JSON body.
• Split each line on the first `: ` only. Values such as ISO timestamps can contain colons.
• A field with no value (for example sim when unavailable) is an empty string after the colon, not the word null.
• All values are plain strings. Convert iridiumDataId, dataLength, satelliteLatitude, satelliteLongitude and satelliteRadiusKm to numbers, and dateTime / endTimeOfSession to dates, yourself.
• The data field contains even-length hexadecimal, optionally prefixed with 0x, not decoded text. For example, 48656c6c6f represents the 5 bytes of Hello. Payload strings containing newlines are rejected before delivery.
• The HTML part is the same data as a two-column table. Each value is inside a <code> element and &, <, >, " and ' are HTML-escaped; unescape them before use.
• The IMEI is also in the subject line, which is a convenient routing key before opening the body.

const NUMERIC = new Set([
  "iridiumDataId", "dataLength",
  "satelliteLatitude", "satelliteLongitude", "satelliteRadiusKm",
]);

// `text` is the text/plain body from your mail library (e.g. mailparser).
function parseTelemetryEmail(text: string) {
  const message: Record<string, string | number | null> = {};
  for (const line of text.split(/\r?\n/)) {
    const split = line.indexOf(": ");
    const name = split === -1 ? line.replace(/:$/, "") : line.slice(0, split);
    if (!name) continue;
    const raw = split === -1 ? "" : line.slice(split + 2);
    message[name] = raw === "" ? null : NUMERIC.has(name) ? Number(raw) : raw;
  }
  return message;
}

A frame is a 3-byte protocol header followed by one or more information elements. All multi-byte integers are big-endian.

1. Read the first 3 bytes. Byte 0 must be 0x01; bytes 1-2 are the big-endian length of everything that follows.
2. Read exactly that many bytes from the TCP stream. The sender closes the connection after one frame.
3. Loop while bytes remain: read 1 byte for the IEI and 2 bytes (big-endian) for the element length L, then read L body bytes.
4. Dispatch on the IEI and decode the body using the field tables. Skip unknown IEIs by advancing L bytes so future elements do not break your parser.
5. Validate: the IMEI is 15 digits, the MO header body is 28 bytes, and the sum of (3 + L) over all elements equals the overall message length.

function parseDirectIp(frame: Buffer) {
  if (frame[0] !== 0x01) throw new Error("Unsupported protocol revision");
  const total = frame.readUInt16BE(1);
  if (frame.length < 3 + total) throw new Error("Incomplete frame");

  const result: Record<string, unknown> = {};
  let offset = 3;
  const end = 3 + total;

  while (offset + 3 <= end) {
    const iei = frame[offset];
    const length = frame.readUInt16BE(offset + 1);
    const body = frame.subarray(offset + 3, offset + 3 + length);
    offset += 3 + length;

    if (iei === 0x01) {
      result.messageReference = body.readUInt32BE(0);
      result.imei = body.toString("ascii", 4, 19);
      result.sessionStatus = body[19];
      result.momsn = body.readUInt16BE(20);
      result.mtmsn = body.readUInt16BE(22);
      result.sessionTime = new Date(body.readUInt32BE(24) * 1000);
    } else if (iei === 0x02) {
      result.payload = Buffer.from(body);
    } else if (iei === 0x03) {
      const south = (body[0] & 0b10) !== 0;
      const west = (body[0] & 0b01) !== 0;
      const coord = (i: number) =>
        body[i] + body.readUInt16BE(i + 1) / 1000 / 60;
      result.latitude = (south ? -1 : 1) * coord(1);
      result.longitude = (west ? -1 : 1) * coord(4);
      result.radiusKm = body.readUInt32BE(7);
    }
  }
  return result;
}

{
  "iridiumDataId": 123456,
  "imei": "300234012345678",
  "sim": null,
  "messageId": "42",
  "dateTime": "2026-10-05T18:30:00.000Z",
  "endTimeOfSession": "2026-10-05T18:30:04.000Z",
  "dataLength": 5,
  "data": "48656c6c6f",
  "satelliteLatitude": 32.7157,
  "satelliteLongitude": -117.1611,
  "satelliteRadiusKm": 12,
  "sessionStatus": "COMPLETE"
}

This is the request sent to your customer endpoint, not the internal request to the outbound service. Delivery-control fields such as destinationId, deliveryMethod, destination, deliveryId, geoDataFlag, and attemptCount are not included. The example data is hexadecimal for "Hello": 10 hex characters representing 5 bytes.

Return any HTTP 200-299 status to accept the message. No response body or JSON schema is required; 204 No Content is sufficient. The service uses only the response status and does not interpret the body.