My solution: I put the two cards on different sides of my wallet and open it to use whichever card is needed. If the radio frequencies [used] are close to each other, you can have a conflict. But fortunately, not many cards have this problem. Our suggestion to users experiencing this problem is to physically separate the two cards for use.

Of course, if your building has adopted Octopus access-control service, the best solution is to use one single Octopus card for both payment and access control.

Another possible solution is to have the Octopus transponder located elsewhere, like in a mobile phone housing or a wristwatch. We do offer these products.

One technology currently under development is near field communication, or NFC--it's a joint venture between Sony and Philips. It links two electronic devices like a card with a mobile phone--it's like Bluetooth but requires closer proximity, about 10 centimeters. The standard is compatible with contactless smart cards, and will allow users--in the near future--to use a compatible phone and SIM card like an Octopus card. It's being used now in Japan.

Our evolution into the retail space was planned. When we drafted our original specifications to build the system, we included these retail applications, as well as access control. People had already been talking about different uses of smart cards for some time, so we designed the system to accommodate future capabilities. And right now Hong Kong is one of the more successful locations using smartcard technologies.