EC200A-EU Cannot Work with Telkomsel Indonesia SIM Card (Same Firmware, Different Behavior)

IoT Modules LTE-A Module
1

Hello everyone,

I am currently facing a very confusing issue with several Quectel EC200A-EU modems and would really appreciate any suggestions.

I have a total of 5 EC200A-EU modems.

  • 2 modems work perfectly with a Telkomsel Indonesia SIM card.

  • 3 modems cannot work with a Telkomsel SIM card.

  • However, all 5 modems work normally with other operators, such as XL Axiata, Indosat, and Tri.

To troubleshoot the issue, I have already tried the following:

  • Updated all modems to the same firmware version:

    EC200AEUHAR01A30M16_01.300.01.300

  • Verified that the firmware upgrade was successful.

  • Tested the same Telkomsel SIM card on different modems.

  • The same Telkomsel SIM works perfectly in the 2 working modems, but it does not work in the other 3.

  • Other operators (XL, Indosat, Tri) work normally on all modems.

2

Hi Fahruddin,

The way you’ve narrowed it down already tells us a lot. Same SIM, same firmware, and XL/Indosat/Tri all working on all 5 units rules out the SIM, the APN and the core firmware. Since it only fails on Telkomsel and only on 3 units, this is almost certainly at the radio/band layer rather than provisioning.

Here’s the reasoning on why it’s Telkomsel specifically: your modules are the “-EU” variant. Telkomsel relies heavily on B40 (2300 MHz TDD) for LTE, on top of B3 (1800). XL, Indosat and Tri all have solid FDD coverage on B3/B1/B8 that an EU-band SKU handles fully — but B40 (TDD 2300) is an APAC band that a European variant is least likely to lock onto cleanly. So Telkomsel is the one operator whose coverage leans on the band your units are weakest on.

To confirm it, test a working unit and a failing unit side by side, same location, same SIM (so coverage isn’t a hidden variable):

  1. On a WORKING unit registered to Telkomsel, check the band it’s actually using:
    AT+QNWINFO
    e.g. +QNWINFO: "TDD LTE","51010","LTE BAND 40",38400 ← this is the band to focus on
  2. On a FAILING unit with the same SIM:
    AT+CEREG? (registration state)
    AT+COPS=? (does 51010 / Telkomsel even appear in the scan?)
    AT+CEER (reject cause if it tried and failed)
  3. Compare band config across both:
    AT+QCFG="band" → compare the <ltebandval> hex mask; B40 = 0x8000000000

How to read it:

  • If Telkomsel doesn’t appear in AT+COPS=? on the failing unit, it can’t see that band. Align the band mask first (AT+QCFG="band" saves automatically and takes effect immediately, no reboot). If the masks already match the working unit, it’s pointing at RF/antenna on that band.
  • If it appears but registration is rejected, the AT+CEER cause is the key: #15 (no suitable cells) again suggests weak/absent B40 reception; #7/#14 (EPS/LTE not allowed) would be more of a network-side angle to raise with Telkomsel.

One quick hardware check: swap the antenna between a working and a failing unit. If the fault follows the antenna, the module is fine — a marginal 2300 MHz path drops out on B40 first while the lower FDD bands still attach, which fits your symptom.

If you can post the AT+QNWINFO from a working unit and the AT+COPS=? / AT+CEER from a failing one, that should pin it down.