CDMA Technology
Members Sign-In
A Global Concern

By Michael McClelland and Apple Bass GTE GSI

The issue of international roaming is about to intensify. The global village is coming to the wireless industry, and with it comes the challenge of making its many disparate parts work together. Demand is on the up from all population sectors. Studies abound weighing the pros and cons of the various wireless technologies that are currently being developed. In the end, however, it’s about the consumer and how operators can meet their needs.

The demand for global roaming is on the up, and it isn’t just the jet-setting business user that’s setting the pace. Satellite providers are investing billions of dollars in infrastructure and they are expected to market heavily in order to recoup their investments. What will they be marketing? Seamless global roaming.

Until now, CDMA operators in general have not really pushed global roaming, so it isn’t high in the consciousness of their subscribers. That’s going to change dramatically over the next few years. In order to protect their most valuable market segment, wireless operators must step up to the plate.

Interoperability is the key to making seamless global roaming a reality. Six major standards are currently in use around the world: analog, CDMA, TDMA, digital AMPS, GSM and PDC. For seamless global roaming to take place for the CDMA operator, the following must occur:
· Wireless Air Interface — multi-mode handsets and other terminal equipment must be developed that can be used in the different types of networks.

  • Network Connectivity — for validation, registration and call delivery.
  • Numbering plans and software solutions — to handle potential number duplication.
  • Roaming agreements — operators must establish more agreements with diverse roaming partners.
  • Roamer billing data — various formats must be transferred between operators.

Because manufacturers offer various handsets using different frequencies (800, 900, 1800 and 1900 MHz) and different technologies (CDMA, TDMA, GSM and PDC), it’s important that the operator’s potential roaming partner has the ability to service the roaming user’s handset on the network. The handsets have standards associated with station numbering, and once the telephone is powered on, the mobile scans the available channels. In some cases, operators trying to cut down on churn arrange for handset vendors to limit the channels available. Because of this, the handset may need to be specially programmed before roaming abroad. Manufacturers are also currently addressing the multi-mode handset and terminal equipment issue.

Network connectivity for the purpose of validation and call delivery can be accomplished by connecting to each individual roaming partner and testing with them or by using a network backbone provider already interconnected with operators. Testing the network to each operator can be very time-consuming, so it makes sense to use the latter approach. There are a number of companies connected to SS7, X.25 and C7 gateways that provide network connectivity for operators and offer translation between the various standards.

Network call routing issues are complex. For the routing of signaling messages there is an X.25 solution that enables IS-41 messages to be sent over a leased line connected to a converter or switch, available from most vendors. With this solution there are fewer issues, and by using a virtual private circuit the network costs are held to a minimum.

The next challenge is to address numbering plans to insure that conflicts do not exist with other operators. Several operators intent on offering international roaming have experienced conflicts between their telephone numbers and other operators’ numbers. That fact alone has severely impeded the launch of their international roaming service. The International Forum for AMPS Standards Technology (IFAST) administers the numbering plans. Most operators actively participate in IFAST meetings before they start roaming. Once the numbering plans are verified, the operators can proceed with addressing the business issues of international roaming. The business side involves establishing roaming agreements, fraud prevention and data clearing services, as well as the ongoing management of the roaming business.

The CDMA Development Group (CDG) offers a sample roaming agreement that can be used as the basis for a contract between operators. The contract is typically on a bilateral basis and provides the terms and conditions for reciprocal services to roamers. Some provisions likely to be in the roaming agreement include which country’s law will prevail, how the currency exchange rates will be handled, how customer service will support foreign languages, and what tools will be implemented to combat fraud.
Various types of fraud (tumbling, cloning and subscription) are prevalent in the market today and the amount of money lost annually as a result is significant. Deploying tools and fraud management systems to decrease this exposure is vital in today’s roaming environment. Potential roaming partners may not sign a roaming agreement unless there is some form of fraud protection in place.

Finally, in order to reap the financial rewards that international roaming can deliver, an operator must have systems in place for the transfer of roamer billing data and for the management of roaming partner relationships. The settlement and exchange of billing information and funds is essential for operators. Data clearing houses can receive and process roamer billing records in the various formats — including CIBER used by CDMA operators, and TAP 1, TAP 2, and NA TAP 2 used by GSM operators. If needed, they can even convert them to the version used by the roaming partner.

Today, most operators use a clearing-house rather than setting up the exchange of billing data themselves. Roaming partners using the same billing format don’t experience the same strain on resources that inter-standard roaming poses, but with the advent of satellite roaming and other newer technologies, the number of potential formats is increasing. Roaming agreements and settling roaming revenues between operators will become more complicated because of the different countries and technologies involved. In terms of technologies, for instance, CDMA operators won’t necessarily restrict their roaming agreements to other CDMA operators.
Given that the technological obstacles are removed, an operator will, in the future, be free to establish agreements based on economics. So if a Latin American CDMA operator can strike a more favorable agreement with a United States GSM operator than with a United States CDMA operator, the GSM operator will be the more likely partner.

Because of the complexity of managing global roaming, clearing houses will increasingly perform a more central role. Operators will deal solely with the clearing house, rather than with each of their roaming partners. The clearing house will take care of converting between billing record formats, and its reporting capabilities will provide the intelligence needed to effectively manage their roaming business.

Based in North America, GTE Telecommunication Services Inc. (GTE TSI) operates the world’s largest data clearing house, serving over 170 customers internationally. It offers international, inter-standard roaming solutions and integrated fraud management products and services all linked by networking capabilities.

Heavily involved in the evolution of the mobile telephony industry, GTE TSI participates on many standards bodies and working committees, including the GSM MoU TADIG group, CDMA Development Group, CTIA advisory groups, and various TIA working groups. Specializing in data, voice, video and the Internet, GTE has operations in the U.S., Canada, Dominican Republic, Venezuela, Argentina, Japan and Taiwan with an international network connecting more than 250 locations on five continents. Outside the U.S., GTE serves around 7 million customers.

With six major standards in use around the world, interoperability is emerging as a major issue as operators look to increase their subscribers’ roaming capabilities. Finding a solution for network connectivity, numbering plans, fraud and data clearing can be challenging still, with solutions and services offered by clearing houses such as GTE TSI, international roaming can be achieved rapidly to allow for increased revenues and competitiveness in the global marketplace.