Third form factor could delay SIM advance

The SIM - the subscriber identity module - has come a long way since its conception in 1988 as an authentication module with a limited amount of memory. Like most things electronic, its size has decreased almost in direct inverse proportion to its processing capabilities.

But now, says Graham McKay, CTO of JSE-listed Prism Holdings, the barriers to future reductions in the SIM size are not electronic, but physical, mechanical and logistical. And until this is overcome, the SIM won`t reach its full potential, beyond its advanced state today as a multi-application platform providing interoperability and inter-working between different access technologies from GSM to WiFi to W-CDMA (Wideband Code Division Multiple Access).

"The original SIM cards were the size of plastic credit cards with just 4K memory. Today, SIMs are considerably smaller but can hold 64K or even 128K memory. And the 1MB SIM is not far off. This size reduction has gone hand-in-hand with the physical reduction in size of cellular handsets.

"However, while virtually every component within the handset has become smaller and lighter, one critical component has remained the same: the SIM socket or connector. The result is that the SIM, and its connector, are probably the largest components in today`s cellular phones," he explains.

According to McKay, there is little to stop the manufacture of even smaller SIMs - SIMs that can be embedded in devices other than cellular phones.

"Mobile handsets themselves are unlikely to get much smaller - they would be too awkward to handle. But if a SIM can be embedded in another device, such as a headset - or a car steering wheel, for example - there would be no need for some additional mechanism to allow for hands-free driving. Imagine if all cars came with a built-in cellphone along with its CD shuttle and aircon!" he says.

Technically, McKay continues, this is quite possible.

With the advent of 3G, the SIM has evolved into what`s called the USIM - the universal subscriber identity module. USIM equips the SIM to play a key role in crucial aspects of 3G - and even 2.5G - such as managing security access, virus intrusion, customer profiles, manual authentication, downloading and a new phonebook allowing for the management of additional information such as fax numbers and e-mail addresses.

The USIM will have the ability to store applications for additional services offered by network operators such as prepaid service activation and control, information services, directory services, mobile banking, micro-payments from an electronic purse or connectivity to a bank account much like a debit card, and ticketing.

Already, there are network operators in Japan and Europe that are delivering SIMs with up to 70 different applications already embedded and more available for download from the Internet.

"The issue facing operators now is that the SIM has to be backwardly compatible: it has to be able to work in every current - and future - handset or device. And this requires what`s known as the 3FF, or third form factor - the mechanism or driver that will hold the SIM in place in the access device and enable it to be connected to the network. When we moved from the credit card-sized SIM to today`s 2FF (second form factor) SIM, the form factor was basically the same: we simply removed the chip from the plastic if the handset required the smaller SIM. However, everyone received the SIM in the same format.

"But the physical dimensions and characteristics of the 3FF SIM will be totally different. Operators cannot simply switch over to 3FF: there are millions of handsets out there that will not be compatible with 3FF. Ensuring subscribers receive the correct size SIM for their access device - whatever that device may be - could be a manufacturing logistical nightmare," he explains.

However, McKay believes that once the 3FF dilemma is resolved - and it will be with the development of a global 3FF standard - there will be an upsurge in the development of smaller devices for data transmission which offer additional communications and financial applications.

"The SIM will achieve its full potential and become a personal mini-computer that is always on and always connected," he concludes.