CDMA: RUIMing the GSM Edge?

Recently, Reliance announced that its handsets were going to be SIM-based.
The announcement surprised many, especially because of the general perception
that a CDMA handset can’t be SIM-based.

In GSM phones, a SIM–subscriber identity module–is required to identify a
subscriber to the wireless network. It is a key element in over 700 million
GSM mobile phones, which represent about 70 percent of the mobile handset
market.

But why exactly does a handset require a SIM? The reason is ‘smartness’.
A SIM is actually a tiny computer in the phone. It has memory (for data and
applications), a processor and the ability to interact with the user. Currently,
SIMs typically have 16 to 64 kb of memory, which provides plenty of room for
storing hundreds of personal phone numbers, text messages and value-added
services. For years this was GSM’s ‘smart’ advantage over CDMA. A SIM
would allow a subscriber to roam between otherwise dumb wireless handsets as a
subscriber’s personal information and phone settings could be switched to
different phones. In case of CDMA, however, subscribers were stuck with the
phone they bought. These phones typically had a chipset that could not be
removed and carried to another phone.

Following
approval from the Telecommunications Industry Association (TIA) in 2002, SIM-like
cards can now also be used inside phones operating on other networks,
particularly CDMA. The chip used inside a CDMA phone, however, goes by a
different name–removable user identity module (RUIM).

RUIM has essentially the same functions in a CDMA phone that a SIM card has
in a GSM phone. The RUIM chip can identify the user to the network with a high
level of security, so that the ability to make certain transactions, such as
stock trading or banking, is there. In future, these cards can even be used as
debit cards, credit cards or bus passes. The RUIM has another ace up its sleeve
over the SIM. Unlike the SIM, it offers to be a 3G solution for global roaming
between CDMA and GSM networks. In other words, it will allow users to shift
between GSM and CDMA phones seamlessly, with all their personal information
stored on the tiny chip.

With the world poised to ride faster, 3G networks, we still face
interoperability-related problems. RUIM is going to be a boon here, as it can
serve as another brick in the foundation of global wireless under the coming 3G
standards. While 3G will be based on the CDMA technology, there still are going
to be two standards, namely CDMA2000 and IMT-2000. The former will be the
evolution of existing CDMAOne networks (being used by Reliance in India), while
the latter is the wideband-CDMA standard for GSM networks. This kind of
flexibility is required, as GSM is the dominant standard in Europe.

Now let us look at the Indian scenario. CDMA has been in existence in the
country for a couple of years now, with MTNL having the distinction of being the
first to launch its services. The service, launched in Mumbai and Delhi, was
quite a hit, but MTNL soon ran out of network capacity. It re-launched the
service in January 2002 after augmenting the capacity.

At present, there are four CDMA players in India–BSNL, MTNL, Reliance and
Tata Teleservices (TTSL). Reliance, with its Reliance India Mobile brand, spans
18 circles; while TTSL, with its Tata Indicom brand, is present in Andhra
Pradesh, Delhi, Gujarat, Karnataka, and Tamil Nadu, and is planning to foray
into Kerala, Punjab, Haryana, and UP. Initially, bundling of handsets or helping
subscribers get handsets financed appeared to be a brilliant move undertaken by
Reliance. But the company soon realized that offering flexibility would be a
much better idea as not many users wanted to be locked into one service and one
handset for a period of three years. That’s when it came out with the idea of
going for SIM-based handsets.

Currently, the approach that all CDMA operators in India follow for
provisioning a new subscriber on the network is based on the handset’s
individual identification number–the electronic serial number (ESN). This
number can be found on the back of the handset under the battery and is usually
eight characters long. The operator keys in this ESN number into the network.
This makes the subscriber and handset completely network dependent. This will
change with RUIM-based handsets.

However, it does not make much sense if only Reliance goes for RUIM-based
handsets. For the user to be able to move from the Reliance network to, say,
Tata or BSNL network, those networks must also support RUIM-based handsets. If
in the near future other operators also follow the move it’s going to usher in
a new era of CDMA service in India.

Saurav Mitra