How to Keep a Phone Number Cheap: Comparing Low-Cost Voice & SMS SIMs

The short answer: if all you really need is to keep a phone number alive, a stripped-down voice SIM focused on calls and SMS can cost just a few dollars a month. Take it a step further with a “split” setup—keep your number on a cheap voice plan and move your mobile data to a cost-efficient eSIM—and your monthly bill becomes far easier to manage. This guide compares low-cost Japanese voice SIMs that work well for keeping a number, then shows how to pair them with the data-only Bloomy eSIM, explained in plain terms for first-timers. For the basics of phone numbers and SMS, see our phone number & SMS guide.

* Pricing, data allowances, and terms can change. Figures below are approximate guides as of June 2026 and are billed in Japanese yen; any US-dollar amounts are rough conversions only. Always confirm the latest pricing with each provider before signing up.

The bottom line: a voice SIM can keep your number for just a few dollars a month

“I want to keep my phone number, but the big carriers are expensive”—a very common situation. The reality is that if you narrow a SIM's job down to just calls and SMS (the kind used for phone-number verification), a low-cost voice SIM can realistically keep your number for only a few dollars a month. Two points make this work:

• You don't have to change your number: with number portability (MNP) you carry your current number to the new plan. It's an add-on tweak where nobody loses out.
• Data can live separately: instead of forcing heavy data usage onto a voice SIM, you can hand it off to a cost-efficient, data-only eSIM.

Below, we line up low-cost voice SIMs that suit keeping a number and lay out, honestly, who each one fits.

Low-cost voice SIMs we recommend for calls and SMS only

Here are voice SIMs that work well for keeping a number, presented neutrally. There's no single “right” answer—your choice comes down to going for the absolute cheapest vs. paying a little more for hands-off peace of mind.

SIM (plan)	Approx. monthly (yen / ~USD)	Monthly data	Call rate	Network	Best for
Nihon Tsushin SIM – Gouriteki Simple 290	¥290 (~$2)	1GB	¥11/30s (~$0.07)	docomo network	A hands-off, fixed-rate plan you can leave running. Good all-rounder
HIS Mobile – Jiyu Jizai 2.0	¥290 (~$2)	¥290 if under 100MB	¥9/30s (~$0.06)	docomo network	People who want low per-call costs. 5G supported
mineo – Mineo Mai-soku Super Light	¥250 (~$1.70)	Unlimited at up to 32kbps	¥22/30s (~$0.15)	—	People who only want calls and SMS verification (setup fee approx. ¥3,740 / ~$25)
irumo – 0.5GB	¥550 (~$3.70)	0.5GB	Separate	docomo network	People who value the stability and reassurance of a major carrier's network
povo2.0	¥0 base (keep-alive needs a cheapest top-up once every ~6 months ≈ a few dozen yen/month effective)	Add as needed	¥22/30s (~$0.15)	au network	The rock-bottom option, for people who can manage one action every six months

* povo2.0 has a ¥0 base fee, but if you don't buy a paid top-up within 180 days your line may be suspended and the number lost, so it cannot be kept “truly free forever.” Pricing and terms are revised from time to time, so check each provider's latest official information before applying.

What each SIM is like, and who it fits

Nihon Tsushin SIM – Gouriteki Simple 290

Around ¥290 (~$2) a month with 1GB included; extra data runs about ¥220/GB (~$1.50). There's no minimum term or cancellation fee, and because it's a flat rate you can leave it running without your number quietly lapsing. A good fit if you want a balance of keeping a number plus a little data and calling.

HIS Mobile – Jiyu Jizai 2.0

Also in the ~¥290 (~$2) range, with a low call rate of ¥9/30s (~$0.06). If you make a fair number of calls, the per-call savings add up. 5G supported on a docomo-based network.

mineo – Mineo Mai-soku Super Light

At around ¥250 (~$1.70) it's about as cheap as it gets, but data is capped at up to 32kbps—so slow that real browsing isn't really the point. It suits people who just need calls and SMS verification. Note the setup fee of roughly ¥3,740 (~$25) up front. It pairs especially well if you plan to cover data with an eSIM (more on that below).

irumo – 0.5GB

Around ¥550 (~$3.70) a month for 0.5GB. It's a touch pricier than the others here, but it's chosen by people who value a major carrier's reassurance and a stable network. Pricing can be revised, so confirm the latest figures officially.

povo2.0

The ¥0 base fee is the draw, and the cost to keep a number is about as low as it gets. The knack is simple: “just buy the cheapest top-up once every six months.” The catch is that forgetting the purchase within each 180-day window risks losing the number, so it assumes you're willing to manage it yourself. Best for people who prioritize price over convenience.

“Cheapest” vs. “hands-off peace of mind” — how to choose

If you're unsure, these criteria make the decision easier:

• Keep it as cheap as possible → povo2.0. Effective cost is about as low as it gets, but you'll need to manage that twice-a-year action.
• Keep it hands-off and worry-free → fixed-rate plans like Nihon Tsushin, mineo, or irumo. Little risk of losing the number to a forgotten purchase.
• You make a lot of calls → lower per-call options like HIS Mobile or Nihon Tsushin.
• Calls and SMS verification are all you need → mineo Mai-soku Super Light, with data covered by an eSIM.

It's worth checking whether your device supports these SIMs—our compatible-devices page can help.

Keep your number as-is and cut only your data cost: the “split” approach

The voice SIMs above are strong at keeping a number, but costs climb if you use a lot of data. That's where it helps to know about the split (dual-SIM) approach: calls and SMS on a cheap voice SIM, data on a data-only eSIM.

The data half of that pairing is the data-only Bloomy eSIM. To be upfront with you:

• Bloomy is data-only. It does not include a phone number, SMS, or voice calls.
• That means your number and SMS verification stay on your voice SIM, exactly as before (your number doesn't change).
• Calls and messages through apps like WhatsApp can work wherever you have a working data connection.
• As a data-only eSIM, Bloomy is subject to a fair-use policy, and real-world speeds depend on the local network, your device, and your location.

Approximate Bloomy data plans for use in Japan are below (rough guide as of June 2026; confirm the latest on the comparison page).

Data	Days	Approx. price (USD)
1GB	7 days	~$1.70
3GB	30 days	~$2.90
10GB	30 days	~$7.50
20GB	30 days	~$13
50GB	30 days	~$27

What a split setup might cost per month (examples — guides only)

Here's a rough monthly picture for “keep your number on a voice SIM + data on an eSIM.” The benchmark is a major carrier's 20GB tier (roughly $25+ a month without discounts). These are just examples and will vary with your current contract and usage. It won't necessarily be cheaper, and it won't necessarily be half the price.

• Number = povo keep-alive (cheapest top-up once every six months ≈ a few dozen yen/month) + data = Bloomy 20GB ~$13 → about $13 total. The lowest-cost way to keep a number (but you must manage the six-month action and lapse risk).
• Number = Nihon Tsushin SIM ~$2 + data = Bloomy 20GB ~$13 → about $15 total. The hands-off option where a forgotten action is unlikely to cost you the number.
• Number = mineo ~$1.70 + data = Bloomy 10GB ~$7.50 → about $9 total. For people who keep the voice SIM for calls/verification only and buy just the data they need.

Compared with a large high-data plan, in some cases this can lower your monthly mobile cost. When comparing against budget tiers, think in terms of the actual difference for your data needs and conditions rather than expecting a fixed “half price.” Pricing and terms change, so always confirm the latest with each provider.

Things to watch when setting up and switching

Checking these before you start a split setup will save you headaches:

1. Does your device support dual SIM? You'll need physical SIM + eSIM, or two eSIMs (on iPhone, roughly the 13 and later). Confirm on the compatible-devices page.
2. Assign each line's role: set the default voice line to your voice SIM and mobile data to the eSIM (Bloomy). For eSIM installation steps, see the setup guide.
3. Receive SMS verification on the SMS-capable voice SIM: bank and app SMS codes go to your voice SIM's number (Bloomy's data eSIM cannot receive them).
4. Carry your number with MNP: to keep your current number, use each provider's number-portability process. Follow the official guidance of the plan you're switching to.

A small amount of data on the voice SIM also serves as a backup if the eSIM ever has trouble.

Summary: which one is right for you?

If your goal is purely keeping a phone number, povo2.0 is about the cheapest (with that twice-a-year task), while fixed-rate plans like Nihon Tsushin SIM, mineo, and irumo are the hands-off, worry-free candidates. Add the split approach—number on a voice SIM, data on a data-only eSIM—and your monthly mobile bill gets much easier to rethink. Bloomy is data-only with no number or SMS, but in exchange you can pick exactly the data you need. Compare data, days, and pricing on the comparison page, browse the phone number & SMS guide and our FAQ, and find the combination that fits you. Pricing and terms can change, so we recommend confirming each provider's latest official details before you sign up.