Hi,

currently it is not possible to query the IMSI of a device via the API.

BUT
the IMSI is delivered along with the lifecycle event when the device registeres it self.
In this case you get forwarded to your configured application url a payload like this.

{
  "reports": [
    {
      "serialNumber": "IMEI:123456789012345",
      "timestamp": 1623278710492,
      "subscriptionId": "63b07b01-4c14-4bba-8bc4-f3a89b3c94ff",
      "resourcePath": "uplinkMsg/0/data",
      "value": "500a060800101a181",
      "customAttributes": {}
    }
  ],
  "registrations": [
    {
      "deviceType": "device",
      "serialNumber": "IMEI:123456789012345",
      "timestamp": 1623278710457,
      "make": "Generic",
      "model": "Sensor",
      "groupName": "TMNL.PROFESSIONAL.CON_0000001204",
      "imsi": "N/A",
      "protocol": "HTTP",
      "tags": "N/A",
      "subscriptionId": "cc48f3fa-7147-4b6d-9fe7-fe5b108e50dc",
      "deviceProps": {
        "device/0/imsi": "IMSI:123456789012346",
        "device/0/model": "Sensor",
        "uplinkMsg/0/data": "500a060800101a181",
        "device/0/manufacturer": "Generic",
        "connectivity/0/port": "62509",
        "connectivity/0/mncmcc": "",
        "location/0/longitude": "",
        "connectivity/0/cellid": "",
        "connectivity/0/ip": "10.0.5.183",
        "location/0/radius": "",
        "connectivity/0/rat": "",
        "location/0/latitude": "",
        "connectivity/0/apn": ""
      },
      "customAttributes": {}
    }
  ],
  "deregistrations": [],
  "updates": [],
  "expirations": [],
  "responses": []
}

You can see the IMEI in the IoT Creators portal because we did some implementation regarding this

Hope this helps a bit.

Regards, Roland