The presentation from last week’s Systems, Cities and Sustainability Mobility Summit are now available. I’ll expand on material new to regular Future Perfect reader’s over the coming weeks. Download Coordination in the Future Urban.

The slide below shows a dual SIM card that can be found in countries with a high proportion of pre-paid phones, a significant number of highly price sensitive consumers and an evolved mobile phone repair culture. It’s a relatively simple street hack that combines two SIM cards into one SIM card form factor – enabling a regular phone to support multiple phone numbers on one phone. Imagine having AT&T + T-Mobile on one device. Click to enlarge photo.

The hack is a response to an existing behaviour – the practice of carrying separate SIM cards in order to reduce communication costs. It typically costs more to call someone on a different operator than the same and before this hack these consumers were willing to put up with the hassle of turning off the phone, switching in a new SIM card, and waiting for the phone to reboot.

Whilst in the short term it’s something that will help consumers shave a few cents off their communication costs, it’s the long term implications that should interest you service and system designers. In many parts of the world the mobile phone number functions as an increasing important form of identity, a single device may be shared amongst a family, friends or even village and the device is the enabler for activities ranging from banking and money transfers to capturing and sharing experiences. If, for the sake of argument a phone number is equivalent to a bank account what does it mean to have two or four or forty supported on one device? And returning to the issues discussed at the summit – what are the implications if the mobile device becomes the primary interface through which we view the city and access its infrastructure?

Yeah you’re right – the hack is far from perfect – since most phone user interface’s are not designed to support multiple SIM cards features such as the call log are compromised. And yeah there are already a few phones out there that support multiple SIM card slots. Clever you. But it is another example of a lo-fi hi-tech something that you can find today on the streets of Accra and Kampala but are unlikely to yet find in Tokyo, London or San Francisco.

SIM card photo photo taken by colleague Younghee Jungr during our Accra field study. Top photo of Ho Chi Minh City during morning rush hour.