8 Replies Latest reply: Dec 11, 2012 4:06 AM by Michel Doueihy RSS

Multi IMSI Approaches


It seems that most multi-IMSI approaches have been focused on solutions to avoid roaming charges for mobile phone use - but it seems that the approach may have some merit to provide an extra level of redundancy for coverage and outage.


Can anyone share their experiences/research/thoughts on multi IMSI (or multi SIM) approaches so that devices can have local IMSIs when they travel to various countries? Some of the topics include:


  1. IMSI selection: tools on the SIM (or device) that detect the MCC/MNC and select the most suitable IMSI*.
  2. Re-registration: tools on the SIM (or device) that detect more favorable networks and force re-registration.
  3. MNO Support: MNO support for the release of IMSIs for multi IMSI solutions.
  4. Dynamic IMSI: tools (typically from the SIM manufacturers) that allow OTA IMSI updates to load IMSIs on the fly.

[* including the logic to determine which IMSI to use when neither IMSI has access to the HPMN].



  • Re: Multi IMSI Approaches

    Hi David,


    I have seen M-IMSI solutions used to support redundancy.


    I can tell you that it is not without its challenges as many of the modules were not capable of supporting the solution out of the box.  In many cases we had to have the customer redesign parts of their solution to support this.


    For that solution, we required that the module support SAT (SIM Application Toolkit) and that functionality be turned on.  We then had to have logic in place as to when to switch between IMSI's.


    As far as the MNO's, I do not know of any of them that support such a solution as it would cut into their roaming revenues.


    Hope this helps,



  • Re: Multi IMSI Approaches

    I know that some network operators hvae SIM cards that have multiple profiles loaded on them typically one is a home profile and the other a roaming profile, this includes a change to a different IMSI where there is more preferential pricing.


    Otherwise you could build a device with 2 SIM sockets and have a switch control by an application processor that allows flipping between the available SIM based on conditions loaded into the logic on the app process. This method does some with certification issues though and cause be problematic to get through the electrical testing...

    • Re: Multi IMSI Approaches



        I have looked at these proposals in the past.


      multi imsi is possible but as Mike states it requires having logic on teh device that will identify the need to switch imsi. The other issue is whether teh operator to support it. There are various security reasons why they would not be interested in this.

      Having two sim cards is a solution but as you point out this also needs to be designed in and you will need to have two subscriptions. Some devices on the markets support multi  sim cards  today and it may be worth looking at those.


      The easiest solution would be to use a roaming sim card. There are a few European operators who are focusiing on this business.   I owuld keep away from opertaors who are simply selling roaming sims cards and look at the few who are looking at  a truly pan european approach. Step one is having the coverage , the bigger issue is always the support.



  • Re: Multi IMSI Approaches



    We have a long experience (and a few patents) on the multi IMSI approach, and believe that yes it is a way to answer two different requirements in M2M:

    - ensure local tarifs for machines moving between different countries (to avoid roaming charges)

    - avoid issues such as bad network coverage or network outage (use a local IMSI in most of the case, and a roaming IMSI when necessary)


    As already mentionned, the device needs to support this, so the best is that the device is SIM toolkit compliant. As this is not usually the case, we have found some solutions to make it work even in non-SIM toolkit compliant device.


    Beside the device, you need also to unify the network side (because multiple IMSI means multiple networks). There are also some solutions for that.



    • Re: Multi IMSI Approaches

      Thanks for the replies - all good information.


      Some specific questions for Romain, can you provide more details on the STK and non-STK solutions for M-ISMI management. And which HLR do you use on the network side and have you used some of the Virtual HLR approaches yet (post here for Virtual HRL).  Which of the SIM card manufacturers have you worked with (or perhaps you work for one of them) ?



    • Re: Multi IMSI Approaches

      Hi Romain , bases on your experiance in the M-IMSI industry. Do you think we can find any operator to work with the M-IMSI.


      We have a product name SIM membranes nano sticker that can stick on top of the sim card (128kb). We have establish the VOIP call through / call back and the roaming features in the sim membranes. However, we have not tested on the roaming because it is very dificult to look for the operator that can provide the M-IMSI, Ki........




      jason chin

  • Re: Multi IMSI Approaches

    We have the SIM Membranes that can stick on top of the original SIM card.

    The Sim Membranes support Multi-IMSI, however we have not test on the features yet.

    May I know any network operator can provide the IMSI , Ki, ......