5G SA billing and BCE: why wholesale roaming charging between operators needs to evolve

On 06-07-2023
Reading time : 6 minutes

Roaming billing processes haven’t changed much in the past 25 years. But the rollout of 5G standalone (5G SA) mobile means a traditional activity will have no option but to change. What can you expect to see?

As the saying goes, if it isn’t broke, don’t try to fix it. That’s been the case with roaming billing processes for a long time. It’s worked well enough, done a satisfactory job, and generally done what operators need.

A solid, time-honored process 

Since roaming began things have evolved. The first international roaming agreement was established back in 1982 between Scandinavia and Finland, called the Nordic Mobile Telephone network, or NMT. The NMT was analogue and, naturally, very simplistic. Roaming has become a global practice in the years since, with long-established technology and processes in place. 

It’s a tried and trusted way of keeping track of roaming subscribers and ensuring they’re billed correctly. Every action a roaming subscriber performs on a visited network creates a record. The network they’re roaming on shares its records with a Data Clearing House (DCH), typically using the Transfer Account Procedure (TAP) format. A TAP file includes a list of the subscriber’s usage details, such as subscriber identification, service, event/call/session detail, duration, and timestamp, with relevant charges listed that have been computed from the wholesale agreement. These TAP files are communicated between partners several times a day.

The billing process itself is built on all operators around the world being able to connect to one another, something they do via a DCH, which guarantees the data interchange between all operators by following GSMA standards processes. Each month, the respective DCH sends a Roaming Traffic Data Report to the domestic network’s Financial Clearing Agent (FCH) to generate an invoice. All this is built on operators having roaming agreements in place with one another, with the agreements covering conditions like network and services implementation, data privacy, fraud management, and the duration of the agreement.

Then, related to the billing itself, processes have to factor in charging and tariffs – which vary from country to country and operator to operator – plus the exchange mechanism itself, and then the actual billing and accounting activities. It’s worked pretty well over the years for operators and consumers.

Shortcomings in the TAP process 

However, there are limitations to the conventional TAP process, and it’s not necessarily suited to all types of billing. Use cases have evolved, and it’s been hard for roaming billing technology to keep pace. 

Small IoT traffic rates 

For example, TAP rates each event, and in the case of Internet of Things (IoT), traffic is made up of many very small sessions that don’t contain enough traffic for each session to be evaluated on its own. It means the individual data sessions cannot be rated, so under TAP, IoT cannot be monetized. 

Linear rating structures 

TAP rating is linear. Wholesale business wants more flexibility in order to define the commercial structure and move to a thresholds models instead of linear, and also combine dimensions. On top of volume charges there is a need to apply a fee to access the network. 

Group agreements 

The TAP process generally aims to exchange charging documents on a monthly basis between two organizations. Alongside this process, groups and operators have established Discount Inter-Operator Tariffs processes that are not standardized today. These cover a variety of commercial charging models, such as allowances, commitments, and bundles. There is an opportunity here to merge the two processes into a unified one that makes things simpler and helps reduce costs for the industry.

Time for a new architecture: enter the BCE era 

The industry has worked hard to develop a new standard because of the limitations mentioned above and the advance of 5G SA technology. According to Juniper Research, the number of roaming subscribers using 5G will grow to 210 million by 2026, up from just 4.5 million in 2021, so it will be impossible to transfer the records for all that massive data use between the various operators in the chain. TAP is too inflexible to support burgeoning use cases and future data demand.

Work kicked off on the new standard in 2018, with GSMA members coming together to design a new standard technology to replace the outmoded TAP process: the common, unified standard called Billing and Charging Evolution (BCE). BCE is tailored to the modern-day roaming subscriber and use case, and it’s able to adapt to the different charging requirements for data, SMS, IoT, and indeed all future new use cases that will come into play as 5G SA goes mainstream. It also covers the Discount IOT process. BCE has already superseded TAP in that industry has agreed that TAP won’t be updated to support new technologies like narrowband IOT (NB-IOT), LTE-M, or 5G SA. For those new use cases moving forward, BCE will be used.

Why it’s time for BCE 

5G SA roaming is a major driver behind BCE gaining momentum. BCE will enable the required flexibility that operators will need to implement new billing models that cover big ecosystems of partners in multiple countries, and it will also enable them to standardize billing between groups. 

Also, operators will be able to decouple usage and charges meaning they can simplify processes and save money through simply doing less work to generate bills. BCE also means being able to stop checking agreements and rating events on a constant, ongoing basis, and do so only at the end of the billing period. It’s a degree of flexibility that seems imperative as IoT connections and 5G connections continue into the billions in coming years and technologies like Voice over LTE (VoLTE) continue growing at steady rates too.

The impact for telcos 

It should be a relatively straightforward thing for telcos to manage, since most of the changes will come at the level of the BCE agent, which will replace the DCH agent. That said, telcos will be required to set up a BCE process with their BCE agent. Telcos will also need to factor in new sources of information that contribute to billing data: at present, each network element produces its own Call Detail Records (CDR). With 5G SA, the charging function (CHF) collects all the records from the different network elements and produces one single CDR. It will also be worth planning for changes in real-time and non-real-time billing architectures, and mediation.

What seems most clear for now is that the two billing systems (TAP and BCE) will continue to coexist for a while. There will be a transition period, though the GSMA says that a number of operators around the world have already implemented BCE, and it is already recognized as the de facto, industry-approved replacement for TAP. 

It’s also already being tested on IoT by testing invoicing according to the number of IoT objects using the service, rather than try to measure traffic. IoT makes for a good use case for trialing BCE, since traffic is relatively low and the financial risk is small. It’s a sensible approach, and a good way to test and improve processes before full 5G SA traffic comes into play where financial risk will be higher, traffic will be much more, and errors will not be acceptable.

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