Question

Discuss How “roaming” service is implemented and the cost of roaming. You must include at least 1 diagram to illustrate your answer.

Answer 1

In more technical terms, roaming refers to the ability for a cellular customer to automatically make and receive voice calls, send and receive data, or access other services, including home data services, when travelling outside the geographical coverage area of the home network, by means of using a visited network. For example: should a subscriber travel beyond their cell phone company's transmitter range, their cell phone would automatically hop onto another phone company's service, if available. The process is supported by the telecommuniction processes of mobility management, authentication, authorization and accounting billing procedures.

Roaming is divided into "SIM-based roaming" and "username/password-based roaming", whereby the technical term "roaming" also encompasses roaming between networks of different network standards, e.g. WLAN (Wireless Local Area Network) or GSM (Global System for Mobile Communications). Device equipment and functionality, such as SIM card capability, antenna and network interfaces, and power management, determine the access possibilities.

Using the example of WLAN/GSM roaming, the following scenarios can be differentiated (cf. GSM Association Permanent Reference Document AA.39):

• SIM-based (roaming): GSM subscriber roams onto a public WLAN operated by:
  • their GSM operator, or
  • another operator who has a roaming agreement with their GSM operator.
• Username/password based roaming: GSM subscriber roams onto a public WLAN operated by:
  • their GSM operator, or
  • another operator who has a roaming agreement with their GSM operator.

Although these user/network scenarios focus on roaming from GSM network operator's networks, clearly roaming can be bi-directional, i.e. from public WLAN operators to GSM networks. Traditional roaming in networks of the same standard, e.g. from a WLAN to a WLAN or a GSM network to a GSM network, has already been described above and is likewise defined by the foreignness of the network based on the type of subscriber entry in the home subscriber register.

The legal roaming business aspects negotiated between the roaming partners for billing of the services obtained are usually stipulated in so called roaming agreements. The GSM Association broadly outlines the content of such roaming agreements in standardized form for its members. For the legal aspects of authentication, authorization and billing of the visiting subscriber, the roaming agreements typically can comprise minimal safety standards, as e.g. location update procedures or financial security or warranty procedures.

TARIFF :

Roaming fees are charged on a per-minute basis for wireless voice service, per text message and per megabyte per second for data service, and they are typically determined by the service provider's pricing plan.

Several carriers in both the United States and India have eliminated these fees in their nationwide pricing plans. All of the major carriers now offer pricing plans that allow consumers to purchase nationwide roaming-free minutes. However, carriers define "nationwide" in different ways. For example, some carriers define "nationwide" as anywhere in the U.S., whereas others define it as anywhere within the carrier's network.

An operator intending to provide roaming services to visitors publishes the tariffs that would be charged in their network at least sixty days prior to its implementation under normal situations. The visited operator tariffs may include tax, discounts etc. and would be based on duration in case of voice calls. For data calls, the charging may be based on the data volume sent and received. Some operators also charge a separate fee for call setup i.e. for the establishment of a call. This charge is called a flagfall charge.

COST ANALYSIS :

A detailed cost analysis for mobile data services is not in the scope of this study. Conducting such a detailed analysis would be complicated. The main reasons for this are :

• For data services there is no benchmark available( as a result of regulation) as is the case for voice rates.
• Cost analysis for data networks may not be realistic because several mobile data networks are currently are under-utilised.
• Cost of UMTS licenses would have to be assigned.

Instead of a detailed cost analysis for data services, cost analysis will be executed on incremental cost basis as follows :

• Cost components for data roaming services will be determined.
• An evaluation will be executed to analyse if these components lead to incremental cost for roamingdata compared to national data.
• Analysis of scenarios for incremental cost for roaming data services.

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