working on Nokia’s first dual‑SIM phones

3 July 2011, 18:47

I am really proud to see the shipping of the first Nokia dual‑SIM phone: the C2‑00. Additionally a second product on the same basis, the hybrid‐touch C2‑03 (aka C2‑06) has been announced. Having been deeply involved with creating these, I would like to share some of my experiences with you.


Although folks on the net write ‘gee, why did it take so long?’, the truth is that developing a dual‑SIM phone is huge undertaking. This is because the software codebase that you start from has been developed—over years, if not ten or more—with the casual, implicit assumption of one user, one SIM.

All of a sudden that fundamental equation is changed to one user, two SIMs. This impacts any software module that deal with voice, messaging or data going over the antenna: i.e. nearly all modules present on a mobile phone, hundreds in total.

a pair is two, no?

And when I say ‘two SIMs,’ I really mean two or more. Dual‑SIM phones do not invent a new way of using phones. They are a response to how single‑SIM phones are used by a large number of users, world‐wide. It is quite normal that these people are using three different SIM cards on any given day. And despite the burden of removing the battery and rebooting the mobile, these SIMs are swapped more times than you would think.

Now imagine what happens to that frequency when one takes that burden away. It was a smart move by Nokia to make one of the SIM slots hot‐swappable.

keeping it personal

When one talks to people about mobile phones for emerging countries, immediately they start speaking of groups, families and villages sharing a single mobile phone. Actually we know what that should be called: a mobile phone booth. Let it be clear that the products I worked on, the C2‑00/03/06, are not designed for that, they are single‐user devices.

Designing the user interaction of a mobile phone booth would be a groundbreaking undertaking. What should Contacts, Messaging or Call logs be like for such a mobile phone booth? I do not know, but certainly not what they are today on all our single‐user phones. If asked, I wouldn’t be afraid to take on the mobile phone booth project, but on the condition that we start from scratch and are supported by a boatload of research to ascertain users’ needs.

structure equals change

Let’s go back to the beginning of the project. ‘One user, two SIMs.’ Changes for dual‑SIM not only uproot the software of a whole phone, but also all user interaction. Same principle: if it has to do—even indirectly—with voice, messaging or data going in or out over the antenna, it is impacted. Yep, just about the whole phone. My job? Making it all work for users.

First thing I did was structure the interaction design part of the project. Having been asked to work as principal designer with a Nokia team of interaction designers, it looked only natural to me that I would design the general solution for dual‑SIM user interaction for the whole phone, and to deliver it in the form of interaction patterns.

The other part of this plan was that I immediately empowered my team of Nokia designers. Each of them was to take charge of a key part of the phone and redesign it, based on the general patterns that I designed. This straightforward plan addressed the questions of how to deal with a project on this grand scale and how to do it with consistency.

nowhere to hide

Also clear on day one was that existing competitor dual‑SIM phones were doing a dreadful job of supporting users with their two, or more, SIM use. To avoid the traps that these had fallen into—identifying SIMs with just a character (A|B or 1|2); always giving up screen space to show/set what SIM to use next—I started with the following principles:

  • the solution has to be based on the three factors why users bother to use multiple SIMs: saving money; ensuring network coverage; projecting multiple personalities (life/work, etc.);
  • these three factors are not independent—e.g. cost is always an issue; having no network reception spoils the best laid plans;
  • these three factors fluctuate over a given day (mobile tariffs, reception depending on location, switching personalities);
  • only users can decide on the spot, based on the circumstances and their priorities: is it urgent; can I call later; can I afford to pay more; is this marginal reception sufficient; can I give up my privacy?
  • dual‑SIM is not an issue in phone use, most of the time;
  • except, when voice, messaging or data is about to go out over the antenna, then users need full control over which SIM is used for that, every time;
  • also, when voice, messaging or data starts coming in over the antenna, then users need to identify which SIM is involved, every time;
  • make users freely name their SIMs, to express the role each one plays; use these names everywhere;
  • design for three‑SIM use, not just the two that are in the hardware slots; also handle if there is just one SIM present;
  • keep things nimble; do not lock users into using only one SIM; however, support repetitive use of the same SIM.

the right stuff

The solution I designed ticks all the boxes. In it, dual‑SIM is invisible unless there is a user need to interact with it. Then plenty of screen space is given to display the names given to the SIM cards; to show the network reception for both SIMs, at the moment decisions are taken; for direct control by users, with fast click‐through when everything checks out as expected.

Making it work for users is only half my job. Making it buildable is the other half. My solution avoided that hundreds of screens had to be redesigned. Or that hundreds of UI states had to have new input handling added. This saved a massive amount of effort and cost in design, specification, engineering and testing. Those existing competitor dual‑SIM phones did do all this effort, with sub‑standard interaction to show for it.

The overall architecture of my solution had, of course, a make‐or‐break impact on the feasibility of the whole dual‑SIM project. It is professionally satisfying to see how I was able to align the need for minimal disruption from users, technical architects, developers and interaction designers, enabling the success of the project.

the journey is the reward

After nailing the general solution and interaction patterns, a second phase of working with the Nokia designers started. I mentored, consulted with them and reviewed their detailed designs. Particularly fun was the phase where every week I was in a different country, spending two days on‑site with one of the Nokia designers.

We solved all of the tough interaction design questions during those days. This for instance involved going through all the user settings that relate to messaging and deciding for each if it was impacted by dual‑SIM. There is a surprising number of them and about half require detailed knowledge of messaging protocol or GSM legacy.

Normally nobody bothers with these settings, on either the mobile making or mobile using side. But we had to understand and check all of them. To see, if either for a technical reason—does it stop working?—or to enable any of the three factors, a setting had to be differentiated by SIM. This is the infrastructure aspect of going dual‑SIM: it permeates everything and the team of interaction designers has to think through the whole experience.

more fun

One thing I really want to share is how fulfilling it is to work on a useful product like this for emerging markets. During the project there was a sense, of urgency; of the real impact mobile has on the lives of people in these markets; of how much essential value our designs would deliver to end‑users.

In the same period as I worked on dual‑SIM, the Economist ran a special report on telecoms in emerging markets (make sure you read all six parts). First of all, it is humbling to read that the backwards mobile networks… are the ones in the western world. Second, it is uplifting to read that mobile phones in emerging markets are truly improving customers’ lives—their first phone line, first internet, first means of transferring money—and enable customers to raise their income, which lifts a significant part of them out of poverty.

one more for the road

So that is what it was like. A huge and complex undertaking; fundamental change to the whole mobile phone experience; make‐or‐break responsibility for user interaction and project feasibility; avoiding the traps the competition fell into; structuring, mentoring, travelling, consulting; designing the big picture and the obscure details; and in the end, very fulfilling work.

This is why I am really proud to see the shipping of the first Nokia dual‑SIM phone.

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4 comments · post a comment

at 08 July, 2011 20:21,Blogger The Tech Guru commented
I have some feedback regarding usability

1. I learnt that Nokia dual SIMs use Dual Sim Dual Standby technology which means there is only one transciever for both the sims if i am correct, So while receiving a call there is not going to be a problem, but while making a call, the inactive SIM gets cut off from the network. So while on a call on the active SIM, when a person tries to reach caller on the inactive SIM, it says " Mobile is switched off [or] Not reachable " This is a big inconvenience

2. And we cannot add numbers from the hot swappable secondary sim card to the speed dial ? Why is this feature limited ?

3. While on the sim selection menu for a call/sms or choosing the net connection, we can have a small software tweak

example image

Explanation for above image :

When the user goes into the contacts selectin for either calls/messages or even the dialler, we can eliminate one extra click by letting the user select the left softkey for SIM 1 and the actual call button for SIM 2 or vice versa

These are my afterthoughts after seeing a seasoned DUAL SIM user suffer with the C2-01 dual sim phone here in India.. Hope you can take this into consideration and make the forthcoming dual sim phones better..

Thanks ! 
at 01 October, 2011 04:27,Blogger Vikas commented
can i change the names of sims in nokia c2-03 because i have two sims of airtel and i keep forgetting which one is of office use and which one of personal use.if it is possible please reply ASAP 
at 07 October, 2011 18:04,Blogger Unknown commented
hey Vikas,

thanks for pointing out exactly why I made naming SIMs a cornerstone of the dual SIM interaction architecture.

Just a google for “nokia c2-03 naming SIMs” and taking the first hit showed me that the c2-03 is based on my architecture and you can name SIMs.

scroll down in the linked review (to ‘Calling on two SIM cards’), it shows the shortcut how to get to the SIM management menu. 
at 31 January, 2012 13:07,Anonymous Blackberry commented
Dual sim phones are an excellent invention! I bought it as soon as I heard about it. You know what I find funny though is the delay in this invention. We were using cell phones for years and always used to change our sim to use the other no. Thanks to the person who finally got this idea. 

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