EMnify, IMSI switch with EC25

i’m using a EC25 modem via usb on a linux (ppp)
My Sim provider says the sim will switch IMSI until it can find a roaming partner.
However, it requires up to 128 seconds to go through a IMSI switch, and i need at least 5.
I cannot find the configuration of network searching time.

Can anyone help me ?


Hello minh_witti thanks for your question
Sorry I didn’t fully understand your question. Maybe you can describe your question in detail. If the network environment is good, you can register on the network faster. If the network is poor, the module will take longer to register to the network.

Hi, thanks for taking a look.

In details:

the hardware is an off the shelf linux gateway (imx6 + ec25 +yocto).
the sim card is an emnify sim card for international roaming.
we have deployed our gateways in tunisia.

What is happening:
the gateways go online at sun down.
the gateway tried to register a network with the 1st IMSI
the registration failed (as it should) , and the sim card (or the modem ?) switch to the 2nd imsi
the registration failed(as it should) , then something happens, and we’re back on the 1st Imsi rather than going through the 3rd imsi.

Some gateways reach the 3rd IMSI and connects ! but after 10 hours :frowning:
However 1 of 9 works quite well.

example of imsi switch:

Location update rejected from SGSN 2165.MMEC20.MMEGI8000.MME.epc.mnc001.mcc605.3gppnetwork.org (Orange) for IMSI 234500055357610.
Location update rejected from VLR 21650000037 (Orange) for IMSI 295050901437505
New location received from SGSN for IMSI=‘901430001992928’,

As you can see the IMSI switch is working for one gateway and sometimes on 3 other. 4 never works

our sim provider explain the working in


now we have to find why it works and make it work on the other gateways.
Without connectivity we cannot debug. We can assure connectivity for a test (allowing more costly roaming) to configure the modem, but not for normal operations.

I hope it s clear.

Thanks for the support

Hello there
From device side, we do support IMSI switch but device will not proactively clear EFPLMN after IMSI switch as it’s UICC’ responsibility to refresh all needed EFS internally.

As you know, different IMSI can have different FPLMN. Take China for example, China Mobile’s SIM card can’t register on China Unicom and China Telecom, China Unicom’s SIM card can’t register on China Mobile and China Telecom. Then these two kinds of SIM card should have different FPLMN list. That’s to say, after IMSI switch, FPLMN list should be updated by SIM card itself. Our device won’t know which FPLMN should be added into FPLMN and which one should not.
For RPLMN, the validity is also questioned after IMSI switch. For example, RPLMN 72403 for IMSI 724180000949451 is not applicable to IMSI 712040030059451 for current issue. It’s also SIM card’s responsibility to clear or update RPLMN info.

Thanks for the explanation.
Do we have to enable the STK to allow imsi switch ?

as explained in aother imsi switch sim card operator,
we should allow a 180 seconds network search windows before restarting the search.
Is this possible ?

hello there
You should enable STK feature to allow imsi switch, thank you.