Dean Bubley writes: "What I haven't really discussed before is the concept of multi-IMSI SIMs. An IMSI (International Mobile Subscriber Identity) is essentially equivalent to a mobile 'subscription' or 'account'. It's not the same as the device identifer (IMEI) or a specific number (MSISDN)...
Multi-IMSI is something that's been mentioned to me quietly over the last 12-18 months, with increasing frequency. It essentially enables multiple accounts/subscriptions to be loaded onto a single (hardware) SIM. Now at present, it's not possible to have them running simultaneously (eg for separate voice and data connections), and you cannot just 'download' multiple operator personalities (eg Vodafone + Orange + 3) as most major MNOs only issue their own, single-operator SIMs.
But I've been hearing about some interesting potential applications, in a variety of contexts. A number of SIM suppliers offer the cards, and various network-side companies have methods of working with them."
