- Multiple devices
- Multiple SIMs and users SIM swapping
- Multiple SIMs on the same account
- Dual number and dual personality devices
- Dual number SIMs
- Phones with dual SIM slots
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).
Clearly, there are numerous scenarios where people might want a convenient way to have access to multiple MNOs. It could be because of coverage reasons, pricing, roaming, particular service availability, different purposes (eg work vs. personal accounts) and numerous others. Yes, many of the MNOs would prefer you to concentrate all your spend and mobile activity - but I'm talking here about what the user wants.
Generally the current SIM model, for all its security and convenience advantages, mitigates against this. It's difficult to balance a single experience - or payments - across multiple MNOs. There's no easy equivalent to flipping up a laptop lid & seeing 3 different WiFi networks available on the connection manager.
In the past, the only services used were voice and SMS - and so it made sense to have a single service provider, as you had to keep the same number in order for people to reach you. But for other services, there's no reason not to shop around - Internet access from one MNO, perhaps a music download service from another, an enhanced roaming service from a third. It's up to the operators to pitch a convincing bundle - but as phones get cheaper, most users will expect to be able to pick and choose to some degree, even if it just means having two or three separate devices, with one SIM in each.
This is why I refer to the 'Tyranny of the SIM card', especially around areas like data and roaming. The advantages of security start getting outweighed by the disadvantages of lock-in. Yes it's sometimes just a benevolent dictator, but if you take that analogy, then SIM-locked phones are the equivalent of political imprisonment, especially if they are unsubsidised.
The easiest way around this is just to have an unlocked device and SIM-swap, but frankly that's a bit of a pain for most people. The new dual-SIM devices are a more elegant way around the issue, although the range of products supporting this is currently very limited.
There have been various discussions in the past about "soft SIMs" (Intel seemed keen on the concept for laptops, for example), although these have generally been swept away by security concerns (and, behind the scenes, commercial concerns as well).
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.
I also reckon that there are some interesting regulatory and competitive impacts of the technology if it works well: perhaps even the mobile equivalent of an "unbundled loop" in the long term.
I've got some more to say about some specific applications of multi-IMSI, but I'll leave that to a separate post.