What is a mobile data rollover and how long does it last?

Depending on your mobile operator and your monthly tariff, you may have encountered the term data rollover. Data rollover is a feature that mobile service providers can offer on prepaid and postpaid mobile plans.

Data rollover or mobile data rollover is a feature in your monthly mobile data plan that allows you to carry forward unused data in a given month (e.g. March) into the following month (e.g. April). You must, however, consume all of the rolled-over data within one month; otherwise, you will lose it.

We consume mobile data (cellular data) every time we are using any online services without being connected to a fixed WiFi network. Depending on how often we are without our home WiFi, we often use more mobile data in some months and not so much in other months. If you exceed your data allowance in any given month, your mobile operator may charge you for data overage, potentially leading to a bill shock. However, when you don’t consume all your data in any month, it feels a bit unfair that your operator is not rewarding you for the unused data. Data rollover is a feature that does exactly that.

How can data rollover help you and how does it work?

Data rollover allows you to take any leftover data from one month to the next month. For example, if your monthly data allowance is 10 GB and you only use 8 GB in March, the remaining 2 GB will be rolled over to the next month giving you 12 GB in April, but you must use this extra 2 GB in April.

When you are about to hit your monthly data allowance limit, it can be a stressful experience. For example, if you get 10 GB of data as part of your monthly mobile data plan and by the middle of the month you already consume 8 GB, life can seem a bit hard with only 2 GB for the rest of the month. Data rollover is a feature provided by some mobile operators on their pay-monthly and prepaid tariffs that can alleviate some of that pain. We don’t always have the same data usage behaviour; there are months when we mostly rely on WiFi only, but there are other months when we do lots of outdoor activities and end up using a lot of cellular data for watching YouTube videos, Facebook updates, Zoom calls, etc. If you have a data rollover feature from your mobile operator, it means that any unused mobile data can be added to your next month’s data allowance. Let’s look at an example to understand how data rollover works.

Suppose you are on a pay-monthly mobile plan from a mobile service provider that gives you 1000 mins, unlimited texts and 25 GB of mobile data as part of your monthly allowance. Let’s now assume that you only consume 15 GB of mobile data in the month of March, which leaves you with 10 GB of unused data in March. Without a data rollover feature, this unused data will not roll over to the next month, and your next month’s data allowance will be 25 GB. But if you have a data rollover feature from your mobile service provider, this 10 GB of unused data will be added to your next month’s allowance, giving you a total of 35 GB in the month of April (25 GB + 10 GB). When you start using mobile data in April, your mobile plan will first use this 10 GB for any cellular data consumption and only when you have used it all up will you start using the monthly 25 GB data allowance.

Example of a mobile plan or mobile tariff

How long does the rollover data last?

As a general rule, your mobile operator or mobile service provider gives you one month to use any rolled over data that you carry forward as part of a mobile data rollover. With data rollover, mobile data can generally be rolled over only once, and if it is not used within a month, it will be lost.

The duration within which the rolled-over data must be consumed depends on how your mobile operator defines data rollover. One common approach in the UK and some other countries is that any unused data can be rolled over from one month to the next, but it must be consumed fully within the next month. If the rolled-over data is not fully consumed in that month, it cannot be rolled over again. For example, if you have 10 GB of leftover mobile data in the month of March and it gets rolled over to April, you must consume all of this 10 GB in April. If you only use 8 GB of this 10 GB in April, the remaining 2GB will be lost. However, one month to consume the rolled-over data is not the only rule out there. For example, Sky Mobile in the UK allows its customers to use rolled over data for up to 3 years.

Is my regular data allowance used first or rolled-over data?

As a general rule in the UK, the rolled-over data that you carry forward gets used first. Once the rolled-over data is fully consumed, then you start using your regular data allowance. In the US, the regular data allowance generally gets used first, and then you start using the rolled-over data.

The approach used for the consumption of the rolled-over data depends on the general rules followed by different markets. For example, in the UK market, the rolled-over data is used first and once it is fully used up, only then do you start using your regular monthly data allowance. However, in the US market, operators like AT&T and Verizon use a different approach, and they allow their customers to use the regular data allowance first and then the rolled-over data.

Let’s use an example to understand this concept. Suppose your regular monthly allowance includes 25 GB of data, and you consume 15 GB of data in June. The unused 10 GB will be available for use in the following month (July). If you are a UK customer (e.g. Vodafone UK), when you start using your cellular mobile data in July, this 10 GB will be consumed first. Once this 10 GB is fully used up, you will start using the regular 25 GB, which is part of your monthly mobile plan. On the other hand, if you are a customer of operators like AT&T or Verizon in the US, you will use your regular 25 GB first, and once it is fully used up, the 10 GB of rolled over data will be available for you to use.

Do all mobile operators offer data rollover?

Data rollover is not a regulation, and mobile operators choose whether to offer it or not. Mobile operators that provide the data rollover can also select the tariffs they want to give the rollover with. An operator can provide data rollover on both postpaid and prepaid mobile plans. For example, in the UK market, mobile network operators (MNO) usually only offer data rollover on prepaid (pay as you go) tariffs. Other service providers in the UK, MVNOs (Mobile Virtual Network Operators), offer data rollover on postpaid mobile tariffs. The concept of data rollover is the same whether it is offered on prepaid or postpaid. Mobile operators can use data rollover on prepaid tariffs as an incentive to encourage customers to top up regularly each month. The duration within which any rolled-over data must be consumed can also depend on the mobile operator. While one month seems to be the general rule most mobile operators use as a data rollover duration, it is possible to offer longer durations. For example, Sky Mobile in the UK provides a data rollover duration of up to three years.

Is data rollover the only solution for data allowance issues?

Data rollover is a good option for those customers who have very limited mobile data allowance as part of their monthly mobile plan because they can benefit from any leftover data. However, if you have an unlimited data bundle, then data rollover offers you no value.

Nowadays, with the 5G cellular services, many mobile operators are already offering unlimited data, which essentially means you don’t have to keep counting how many GBs of data you are consuming. However, it is important to pay attention to your operator’s small prints and the Fair Use Policy (FUP). Some operators have the policy to apply data throttling on specific tariffs if customers don’t abide by FUP. With throttling, your mobile operator can put a cap on the maximum speed you get on their mobile network after you have used up your monthly allowance, e.g. a speed cap of 150 kbps. In other cases, they may restrict you to a lower network technology than you normally use when you exceed your allowance. For example, instead of the 4G LTE network you mostly use, they may limit you to 3G networks to lower your data speed and, therefore, data consumption.

Here are some helpful downloads

Thank you for reading this post. I hope it helped you in developing a better understanding of cellular networks. Sometimes, we need extra support, especially when preparing for a new job, studying a new topic, or buying a new phone. Whatever you are trying to do, here are some downloads that can help you:

Students & fresh graduates: If you are just starting, the complexity of the cellular industry can be a bit overwhelming. But don’t worry, I have created this FREE ebook so you can familiarise yourself with the basics like 3G, 4G etc. As a next step, check out the latest edition of the same ebook with more details on 4G & 5G networks with diagrams. You can then read Mobile Networks Made Easy, which explains the network nodes, e.g., BTS, MSC, GGSN etc.

Professionals: If you are an experienced professional but new to mobile communications, it may seem hard to compete with someone who has a decade of experience in the cellular industry. But not everyone who works in this industry is always up to date on the bigger picture and the challenges considering how quickly the industry evolves. The bigger picture comes from experience, which is why I’ve carefully put together a few slides to get you started in no time. So if you work in sales, marketing, product, project or any other area of business where you need a high-level view, Introduction to Mobile Communications can give you a quick start. Also, here are some templates to help you prepare your own slides on the product overview and product roadmap.

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