FMC003 + Swisscom 22801: Registration Denied / ESM Cause 33 – two different FMC003 work immediately with Salt 22803

Telematics Issue
1

Hello,

I have a reproducible LTE registration problem with two different Teltonika FMC003 devices on Swisscom Switzerland (PLMN 22801).

Both FMC003 units work correctly with Salt Switzerland (PLMN 22803), but fail with Swisscom.

Device / modem information:

  • Model: FMC003
  • FMC firmware: 04.02.00 Rev.602
  • Configurator: 1.8.25_E.OBDRefine_R.2
  • Modem firmware: SLM320PE_TK_V51_U09
  • Both devices use IMEI TAC 86227208

Device 1:
This FMC003 had worked normally with Swisscom for months.
Around 06 September 2026 it stopped sending data.

The device continued recording AVL data internally, so GNSS, movement detection and record generation were still working.

With Swisscom:

  • PLMN 22801 is detected
  • LTE Band 3 is detected
  • network registration fails
  • +CREG: 2,3
  • Registration Denied
  • +ESMCAUSE:33
  • afterwards repeated +CREG: 2,2 / NOSERVICE
  • no PDP activation
  • no TCP connection to server

The same FMC003 with a Salt SIM:

  • PLMN 22803
  • APN: internet
  • +CREG: 2,1
  • +CGACT: 1,1
  • IPv4 PDP context active
  • TCP connection to my Traccar server on port 5027 succeeds
  • AVL records are acknowledged by the server

Device 2:
A second independent FMC003 was tested with the same procedure.

With Salt:

  • registers immediately on 22803
  • PDP context activates successfully
  • TCP connection to Traccar succeeds
  • IMEI and AVL records are accepted

With Swisscom:

  • PLMN 22801 is detected
  • +ESMCAUSE:33
  • +CREG: 2,3
  • Registration Denied
  • afterwards repeated +CREG: 2,2
  • +QCSQ:“NOSERVICE”
  • no successful +CREG: 2,1
  • no PDP activation
  • no TCP connection

Important additional tests:

  • Swisscom SIM works immediately in a Zyxel LTE router
  • multiple Swisscom SIMs were tested
  • APN is gprs.swisscom.ch
  • username/password empty
  • authentication None
  • Auto APN disabled
  • factory reset performed
  • minimal configuration tested
  • firmware upgraded from Rev.13 to Rev.602
  • FPLMN clearing tested
  • cold power cycle including battery disconnect tested
  • Limit Connection Errors disabled during testing

Therefore I now have TWO separate FMC003 units showing the same behaviour:

Swisscom 22801:
Registration Denied / ESM Cause 33

Salt 22803:
Works immediately and completely

This strongly suggests a Swisscom-specific interoperability issue with the FMC003 / MeiG SLM320 modem rather than a hardware, SIM, APN or Traccar problem.

I also found other Teltonika cases where ESM Cause 33 (“Requested service option not subscribed”) was related to IMS / VoLTE behaviour.

The MeiG SLM320 AT command set appears to support VoLTE control, for example AT+SETVOLTE=0.

Questions:

  1. Is there a supported way on FMC003 to permanently disable VoLTE and/or IMS?
  2. Is there a newer modem firmware than SLM320PE_TK_V51_U09?
  3. Is there a supported method to force IPv4-only / data-centric operation?
  4. Is this issue known with Swisscom Switzerland PLMN 22801?
  5. Has Teltonika tested FMC003 / SLM320 with Swisscom after the Swiss 3G shutdown?
  6. Is there a modem NVRAM/network-profile reset procedure supported by Teltonika?
  7. Can Teltonika provide a test/debug firmware or modem firmware for this issue?

I can provide maintenance logs from all four test combinations:

FMC003 #1 + Swisscom = FAIL
FMC003 #1 + Salt = OK
FMC003 #2 + Swisscom = FAIL
FMC003 #2 + Salt = OK

For privacy I have not posted the full IMEIs publicly.

Thank you.

2

Good Day,

This issue requires further investigation of logs to understand the root cause of the issue. Please contact your sales manager and they would assist you with creating a Partner Portal ticket and an engineer will assist you with fixing this issue.

Thanks, and best regards,

Imran S.

3

Hello Imran,

thank you. I am an end customer and do not have a Teltonika Sales Manager or Partner Portal access.

The two FMC003 units were also purchased independently from two different official retailers:

  • FMC003 #1: purchased from Digitec/Galaxus Switzerland
  • FMC003 #2: purchased from Reichelt Elektronik Germany

Therefore there is no single reseller responsible for both devices.

I have already contacted Teltonika through the public Product Support form, but have not yet received a reply.

The issue is reproducible with both independent FMC003 units and I have complete Maintenance Logs for all four combinations:

  • FMC003 #1 + Swisscom 22801 = FAIL
  • FMC003 #1 + Salt 22803 = OK
  • FMC003 #2 + Swisscom 22801 = FAIL
  • FMC003 #2 + Salt 22803 = OK

With Swisscom, both devices reproducibly show Registration Denied / ESM Cause 33. With Salt, both devices register successfully and establish mobile data; the second device also connects successfully to my Traccar server and sends AVL records.

Since the devices come from two different retailers, could you please advise how I can provide these logs directly to the Teltonika Telematics engineering team?

If a Partner Portal ticket is mandatory, should Digitec/Galaxus and Reichelt each create a separate ticket for their respective device, or can Teltonika create one engineering case covering both devices?

Thank you.