Roaming: Road to Profitability

Roaming is a huge revenue-generator. Find out how to maintain those profits into 3G.

Advances in wireless technology have given us the freedom to communicate virtually anywhere. However, these advances have come with some painful restrictions. As service providers and vendors jointly develop solutions for the implementation of global-roaming agreements and multimode, multiband mobile terminals, the significant challenge lies in the interoperability of diverse networks.

Roaming continues to be one of the most profitable revenue sources for wireless providers worldwide. As all service providers look to migrate their networks to 3G and make the vision of seamless global roaming a reality, the future will be full of interim solutions.

In particular, many TDMA-EDGE (IS-136) and GSM providers have been working toward these interim solutions through standards bodies. GSM currently accounts for 55% of the installed- wireless-subscriber base worldwide. Clearly an incumbent, GSM is the dominant technology, and it's still growing (77% subscriber growth in 1999). This data demonstrates that providers, subscribers and the industry as a whole would benefit from graceful interstandard roaming solutions. To support this demand, the GSM Association formed a GSM Global Roaming Forum (GGRF) to extend the reach and influence of GSM roaming. GGRF ensures collaboration between GSM providers and operators using other technology standards (such as AMPS, TDMA, CDMA and iDEN).

To facilitate roaming, service providers must set up signaling links between networks, upload and exchange network-specific data and conduct extensive tests before going commercial. This is a matter of growing complexity as the demand for enhanced services and roaming coverage escalates. Meanwhile, the GSM Association is estimating that more than 700 million roaming calls will be made every month this summer.

SS7 Enabling Roaming in 2G Networks
The basic principles for inter-standard roaming involve certain interfaces between the GSM and ANSI-41 networks. Besides the bearer traffic, voice or data, there are two other critical interfaces: billing (e.g. TAP and CIBER records) and SS7 signaling.

In today's GSM networks, GSM mobile application part (MAP) messaging over SS7 signaling networks is used to support mobility management and services between various public land mobile networks (PLMNs). Likewise, the ANSI-136 and AMPS networks rely on ANSI-41 MAP messaging over SS7 to provide similar functionality. To enable subscribers to roam in both networks, a network interface between GSM and ANSI-41 MAP signaling must be established.

There are products available today that provide network connectivity and MAP protocol conversion to support automatic, 2-way interoperability between GSM and ANSI-136 networks. Because IS-136 networks are established primarily in North America and Latin America, and GSM networks are more prevalent in Europe and Asia, most interstandard-roaming calls are international. This creates a need for international gateways that convert between ANSI SS7 and ITU SS7 protocols — making it critical to manage the valuable data from SS7 networks for enhanced profitability.

Enhancing Profitability
In this competitive landscape, service providers continuously are searching for ways to enhance their bottom-line growth. Because SS7 networks transport all roaming information, sophisticated signaling-management systems that passively analyze this information quickly are becoming critical tools for enhancing roaming profitability.

Service providers are offering new services continuously to roamers and trying to improve targeted marketing efforts. Signaling-management systems assist providers in this effort by determining the roamer's geographical and service preferences. Through signaling-management systems, roamer location and service usage (free-phone, SMS, prepaid, etc) is available to the provider almost instantaneously. Service providers may use the location information to provide other location-based services.

Service providers also can attract roamers and increase revenue by offering new SMS services such as an SMS message to a new roamer, welcoming that person into its network and providing information on new services available. A provider also can send an SMS to the home subscriber roaming in a foreign network, encouraging the use of a roaming partner's network. This could be achieved through the registration information provided by the signaling-management system.

For roaming trends and analysis functions, signaling-management systems generate reports that may be used as intelligence for focused marketing efforts. Additionally, specific reports can be provided or sold to enterprise customers. These types of reports detail the roamer's service usage in both their home network and in a foreign network, helping the customer manage his communications needs and the provider market specific plans and services.

Service providers have difficulty generating revenue from new and existing services with traditional service and capacity-usage measurement and billing systems. With a signaling-management solution, providers gain a detailed view of services such as SMS. They also have the flexibility to charge for SMS services based on either the number of SMS messages or the bandwidth those messages occupy on their SS7 networks. Bills also could be generated for interconnect providers bringing their SMS traffic into a provider's network for termination or for the subscribers and roamers sending and receiving SMS messages.

Nothing irritates roamers more than unwarranted registration and authentication failures. Moreover, usually it is simple for roamers to pick another provider by simply navigating through the menu provided in the mobile station. Superior quality of service (QoS), or the perception of it, is very important to both roamers and home subscribers, especially the high-revenue-generating corporate users. If it helps attract roamers to a provider's network, and it reduces the churn rate (estimated at 3% a month), then it offers a strong business case.

Sophisticated signaling-management systems can detect problems faced by roamers, such as registration, authentication, and hand-over failures as well as network congestion, while the calls are in progress — giving providers the opportunity to address these issues before significant revenue loss occurs. Service providers also would have the ability to trace previous unsuccessful calls based on trouble tickets and determine if a legitimate credit is due to the roamer.

Service providers often put a lot of effort into generating service-level agreements (SLAs) and not enough into managing them. For instance, if an SLA exists between two roaming partners, and a QoS level has been set, signaling-management systems enable quick detection of any deviation from the agreed-upon criteria. If the foreign network is not living up to the SLA, the home provider has the flexibility to inform its subscribers to use another network while roaming or to negotiate suitable financial terms with the roaming partner.

Many wireless providers' business models focus on the needs of enterprise customers. Some have direct signaling links connected to the enterprise networks. Typically, the provider must prove it is delivering superior service quality. Whether under the terms of a SLA, or just to retain high-value customers, providers periodically generate reports that demonstrate the QoS they have provided. And signaling-management systems make this task simple. These types of reports provide peace of mind to the customers, making them less likely to change providers.

Implementing a new roaming agreement requires considerable testing before going commercial. There are products available on the market today to perform these tests; however, only signaling-management systems can monitor the effects of a new agreement on the rest of the network. Continuously monitoring all roaming messages on a real-time basis can be a life-saving tool. It will proactively diagnose roaming problems and network behavior, reducing time-to-market with new roaming agreements. Once the agreement is operational, these systems continue to be an excellent tool for operation and maintenance of all roaming traffic.

Roaming in IP Networks
The future of interstandard roaming as we know it is changing with the convergence of GSM and ANSI-136 and the deployment of 2.5G and 3G networks. IP is being successfully deployed in the backbone of the public-switched telephone network (PSTN) and soon will be deployed in wireless networks, since building an IP backbone is more efficient than expanding circuit-switched platforms.

The IETF is developing solutions for IP in the fixed network and its extensions to mobile IP for wireless networks; however, much of the technology still is being debated, and its impact will be limited for quite some time. The goal is to achieve seamless mobility between different networks and technologies. However, this requires a number of key changes including the addition of IP capabilities within cellular networks, better technology for roaming between ISPs, and the convergence of services between IP, PSTN and cellular networks.

Connectivity to the Internet is needed by more people more often and from more locations than ever before, and service providers cannot afford to ignore this demand.

In a 2- to 4-year period, when ANSI-136 and GSM networks converge and begin offering high-speed data services, the core network of GPRS/EDGE will bring new roaming scenarios. According to Comfone, at a high level, these can be distinguished between PLMN roaming and ISP roaming.

• GPRS PLMN roaming: The signaling methods of today will play a key role in tomorrow's wireless networks as well. In this case, the subscriber is registered in the visited network through a signaling exchange between the visited serving GPRS support node (SGSN) and the HLR. For a secure data connection, a tunnel is established between visited SGSN and the home gateway GPRS support node (GGSN). Before the GPRS tunnel can be established, the correct IP address of a suitable home GGSN must be resolved. For this reason, a further signaling relation between the visited and the home DNS services is required.

• GPRS ISP roaming: In this scenario, only a signaling connection to the home PLMN is required but no data connection between the border gateways. The traffic will not be routed back to the home GGSN, and HPLMN only will have limited control over its subscriber behavior and the actual QoS received.

In either of the above scenarios, signaling-management systems still will be needed to monitor the roaming messages and all the previously discussed benefits will apply. In GPRS networks, as in 2G networks, the roaming information will be derived from monitoring MAP links as specified in Phase 3 of MAP specifications.

Signaling/Voice Gateways
The voice-over-IP and signaling gateways are critical components in the integration of PSTN and IP networks today. Likewise, they will play a critical role in integrating wireless networks with other networks.

Just as we have seen in the fixed world, there will be hybrid networks on the wireless side. Soft switches allow service providers to direct their investments towards building IP backbones while protecting their investments in circuit-switched networks. By allowing traditional voice calls to be carried on packet networks, soft switches enable providers to extend the life cycle of existing networks. Moreover, integrating all traffic on a single packet-based backbone will reduce transport costs considerably. This is when roaming as we know it will change. A subscriber now will be able to roam across networks of different types (IP, PSTN, and 3G).

In addition, service providers will be able to develop services for roamers in an IP-based, service-creation environment. This will allow quick development and delivery of revenue-generating services that cross the boundary from telephony to the Web.

Several years from now, when the integration of PSTN and IP will have occurred and 3G wireless IP has been deployed, it will be possible to access IP seamlessly from either a fixed or cellular access. Then, and only then, inter-standard as well internet-work roaming, as we know it today, will end.

Marwaha (samir.marwaha@inet.com) is Inet market strategies director, wireless.