Short answer first: if you want to spend less on mobile but don't want to give up your phone number, there's a middle path — keep the number on the cheapest voice plan you can get from your carrier at home, and add a separate, low-cost data-only eSIM for the part that actually drives your bill: data. That's dual SIM. You're not cancelling anything; you're adding a second line that takes over data. Depending on how much you call and how much data you use, the total can come out lower than a single all-in-one plan. This guide walks through how it works, how to choose each side, how to set it up, and where the catches are — plainly and without hype.
- Keep your existing number and simply add a cheaper eSIM for data — that's the core idea
- Calls and SMS stay on your voice line; data moves to a data-only eSIM, and each side does what it's cheapest at
- Two ways to hold a number cheaply: a bare-minimum prepaid line (lowest cost, needs watching) or a small fixed monthly plan (nothing to remember)
- Bloomy is data-only — no phone number, no SMS, no voice calls — but apps like WhatsApp work wherever you have a data connection
- Whether you actually save, and by how much, depends on your country's pricing and your own usage — so check both before switching
Prices, data allowances and terms change, and they differ a lot by country and operator. Treat every figure below as an illustration of the method, not a quote — confirm current pricing and conditions at the point of purchase.
What is dual SIM? Cutting your bill without changing your number
Dual SIM means one phone can use two lines at the same time. You can assign roles: calls and SMS on your existing number, mobile data on a second, cheaper line.
Because of that split, you can move your data to a different provider without cancelling or porting your number. Your number stays exactly where it is — so family and work contacts, and any SMS verification codes tied to it, keep working as before. If "I'd switch, but I'm afraid of losing my number" is what has stopped you, this is the low-risk version of the change.
If you want to know what your own phone supports before anything else, start with the eSIM device compatibility page.
Why "voice line + data eSIM" tends to be cheaper (division of labour)
A mobile bill is basically two things: the base fee for calls and texts, and the cost of data. For most people, data is where the money goes and where plans differ most. So the dual-SIM approach splits the job:
- Calls and SMS verification: a minimal voice line — the cheapest plan from your carrier at home that keeps the number alive, with little or no data.
- Data: a cost-efficient data-only eSIM — you pick just the allowance you actually need.
The key point is that your number doesn't move. Nothing tied to it breaks, because you're adding a data line rather than cancelling a service. A small bonus: if your voice line still includes a little data, it doubles as a fallback when the eSIM side isn't cooperating.
If you'd rather compare data options across providers first, the comparison articles and the mobile-savings roundup are good starting points.
Choosing a cheap voice line just to hold your number
On the voice side, one thing matters: keeping the number for as little as possible. Broadly, there are two philosophies.
- Go as cheap as possible — a pay-as-you-go or near-zero-fee prepaid line. Cheapest on paper, but you have to keep it active yourself, and an inactive number can expire.
- Keep it effortless — a small fixed monthly plan. Costs a few dollars, but the number survives even if you forget about it entirely.
Names and prices vary by market, so instead of specific plans, here's what the options generally look like and what to check for each. Confirm the current terms with the operator before you commit — and note which network a plan actually runs on, since coverage and device compatibility follow from that.
| Type of line | Rough monthly cost | What to check | Suits you if… |
|---|---|---|---|
| Pay-as-you-go / prepaid, no monthly fee | Effectively near zero, plus occasional top-ups | The inactivity rule — many prepaid numbers expire unless you top up or make a paid use within a set period. Per-minute call rates are usually higher. Confirm SMS is included. | You don't mind setting a calendar reminder to keep the line alive |
| Smallest data plan from a low-cost operator | A few dollars | Cost per extra GB, minimum contract term, and any exit fee | You want "set and forget" with a tiny safety net of data |
| Voice/SMS-focused plan with minimal or heavily throttled data | Among the cheapest fixed options | Whether the data is too slow to be usable at all, plus any activation or SIM fee | You're happy treating this line purely as a number and an SMS receiver |
| Cheapest entry plan from a major carrier | Higher than the above | Whether it's worth the premium for you | You value network stability and a single, familiar bill |
Cheapest, or least hassle?
Bare prepaid lines win on price but come with upkeep and a real risk of the number lapsing. Small fixed-fee plans cost a little more and remove that worry completely. There's no universally right answer — it comes down to whether you'd rather spend a few minutes a year managing the line, or a few dollars a month not thinking about it. For more on numbers and verification codes, see the phone number & SMS category.
Add data with an eSIM | Bloomy data plans
On the data side, a data-only eSIM is the easy piece: you choose the allowance you need, for the period you need it. One important thing to be clear about up front: Bloomy is data-only. There's no phone number, no SMS and no voice calling. That's exactly why it pairs with a voice line rather than replacing one — your number stays with your operator at home. App-based calling such as WhatsApp works wherever you have a working data connection.
Plans are sold by data allowance and validity period, for example:
| Data | Validity | Price (USD) |
|---|---|---|
| 1 GB | 7 days | Check current price at checkout |
| 3 GB | 30 days | Check current price at checkout |
| 10 GB | 30 days | Check current price at checkout |
| 20 GB | 30 days | Check current price at checkout |
| 50 GB | 30 days | Check current price at checkout |
Prices are shown in USD and can change, so the plan page is always the source of truth. To browse by allowance and validity, use the eSIM comparison page.
Working out your own numbers
Rather than quoting totals that won't match your market, here's the arithmetic. Your monthly cost becomes:
| Combination | Monthly total | Compare against |
|---|---|---|
| Number = bare prepaid line + Data = Bloomy 20 GB | Top-up cost spread over the year + the 20 GB price at checkout | Your current all-in-one plan with a similar 20 GB allowance, before any bundle discounts |
| Number = small fixed-fee plan (a few dollars) + Data = Bloomy 20 GB | That fixed fee + the 20 GB price at checkout | Same as above |
| Number = minimal voice/SMS-only line + Data = Bloomy 10 GB | That fixed fee + the 10 GB price at checkout | — (for people who treat the voice line purely as a number and OTP receiver) |
Two honest caveats about the comparison. First, the gap is widest against large-allowance plans from mainstream carriers at full price; against an already-cheap discount brand, the difference may be modest, so compare cost per GB rather than assuming you'll halve your bill. Second, if your plan bundles home internet, streaming or family discounts, unpicking the data side may cost you those, so check the bundle terms before you decide. Once you know your real monthly data use, pick a matching allowance on the comparison page.
Setting it up | How dual SIM works day to day
It sounds technical; it isn't. You keep your voice line as is, add the data eSIM, and tell the phone which line does what.
- Leave your existing voice line alone — don't cancel anything.
- Add the data eSIM by installing it with the QR code or activation details you receive after purchase.
- In your phone's mobile settings, set the roles: calls and SMS = your voice line, mobile data = the eSIM.
- Follow any remaining prompts for your device, such as enabling data roaming on the eSIM line if instructed.
From then on, calls and texts run on your usual number while the internet runs over the eSIM. Menus differ by device and OS version, so it's easiest to follow along with the setup guide. If something won't connect, check the FAQ too.
Check your device and SIM combination first
Dual SIM comes in a few forms, and support depends on the handset.
- Physical SIM + eSIM — if your number is on a physical SIM, adding a data eSIM alongside it is the most straightforward setup.
- eSIM + eSIM — many recent phones (iPhone 13 and later, and a range of Android models) can keep two eSIMs active at once.
Confirm before you buy whether your phone supports eSIM and which combination it allows — the eSIM device compatibility page covers this. It's also worth checking that your phone isn't carrier-locked.
The trade-offs, stated plainly
The downsides are worth knowing before you start, not after.
- Bloomy is data-only. No number, no SMS, no voice calls — so your number and any SMS verification codes (from your bank back home, for instance) must stay on the voice line.
- Bare prepaid lines need upkeep, and numbers can lapse. If a line requires periodic paid activity and you forget, you may lose the number. If tracking that isn't for you, choose the small fixed-fee route.
- You're managing two lines — two sets of billing and two data balances. It's a little more admin, mostly at the beginning.
- Speed and stability depend on the local network, your device and the area, as well as time-of-day congestion. Performance will vary; no plan is fast everywhere at all times.
- Large or "unlimited-style" plans are typically governed by a fair use policy, and may include speed management after a certain amount of use, or conditions on tethering. Check the current terms before purchase.
With those points understood, "keep the number, move the data" becomes a genuinely useful option to have in mind whenever you review what you're paying.
In summary | Keep the number, add cheaper data
Dual SIM is a low-risk way to review your mobile spending: your number stays put, and the data-heavy part moves to a cheaper eSIM. For the number, pick your side — lowest possible cost with a bit of upkeep, or a small fixed fee and nothing to remember. For data, add only the allowance you actually use. Start by checking two things: what your phone supports, and how much data you really get through in a month.
A practical next step: check device compatibility, find a plan that matches your allowance and dates on the comparison page, then skim the setup guide so the install goes smoothly.
