Internet at home / Published: 17 Oct 2026 / Updated: 19 Oct 2026

Can phone tethering replace home internet? Check before adding a line

A practical check of plan limits, device support, real use, data allowance, battery and heat before you sign up for another internet service.

Rigel / Writing and editing

Sources checked: See the sources and dates in the article.

If you live alone and use a computer at home, first check whether your current phone can share its mobile connection. A successful connection does not prove it will meet your everyday needs. Check your plan, the devices and hours you use, and the data and battery impact before you add another line.

Tethering shares a phone’s mobile connection with a computer or tablet. The plan example here is LINEMO Best Plan in Japan; the device steps are for iPhone with iOS 27. Other plans and Android devices have different conditions. Check the official terms for your own plan and model.

List what you use at home

Write down the tasks you need: email, video, online meetings, games, file uploads, and whether meetings need a camera or screen sharing. Note how many devices are used at once, when they are used, whether you take the phone outside, and whether any home device must stay online while you are away.

A home security camera or appliance loses this shared connection when you take the phone with you. If your rental includes internet, check whether that connection already meets your needs. The rental internet checklist covers equipment, fees, and construction permission.

Read your exact plan’s data and fee rules

LINEMO Best Plan currently lists tethering at no extra monthly fee and with no separate application. Tethering normally uses the plan’s high-speed data allowance; it does not add a separate 10 GB for a computer. The plan is ¥990 (tax included) up to 3 GB and ¥2,090 above 3 GB through 10 GB. Other charges are separate. When monthly use exceeds 10 GB, speed is limited to a maximum of 300 kbps through month end; above 15 GB, the maximum becomes 128 kbps. For the 15 GB threshold, additional data purchases are excluded. These are speed limits, not a promise that meetings or video will remain usable.

Additional data is normally ¥550 per GB. Check whether auto top-up is enabled before testing. Some LINE traffic is exempt, but the exemption has exceptions, including some location sharing, sticker shop, and news traffic. VPN or other technical conditions can also use data. Do not assume that a computer’s video is exempt because it uses LINE. Do not disable a work VPN just to reduce data use.

Check the official plan page, terms, LINE data-free conditions, and speed-control notice because prices and rules can change. Speed also depends on indoor reception, congestion, and connected devices.

Check the phone and the connection method

LINEMO’s device list shows tethering support for the SIM-free iPhone 13, but its listed confirmation OS is iOS 15. Apple lists iPhone 13 as supporting iOS 27. Those two facts do not prove LINEMO tested this combination on iOS 27. Check your own SIM, phone, OS, and settings.

Apple describes Wi-Fi, Bluetooth, and cable connections. Supported device counts vary by phone model and carrier. For USB, use a data-capable cable; Windows may need the Apple Devices app or iTunes. Follow your employer’s rules before connecting a work computer. For Wi-Fi, use the password shown in Personal Hotspot settings; Apple says a changed password should use at least eight ASCII characters. Keep passwords private and turn sharing off when finished. Only approve a computer you trust if the phone asks.

Test normal use over several days

Choose several days that include ordinary weekdays and a weekend. This is your own observation period, not a carrier’s free trial. LINEMO My Menu shows “Data remaining” and a usage breakdown. Avoid large downloads if the remaining allowance is low, and check auto top-up settings and limits before you begin.

Record the date and time, selected SIM, connection method, and starting figures from both the phone and carrier account. For LINEMO, note the My Menu “Data remaining” and “Remaining/usage breakdown” figures.
Try the tasks you actually need at their usual times. For meetings, test audio, camera, and screen sharing as needed. Note interruptions, uploads, calls, reconnects, and simultaneous use.
Record the same counters afterward. On iOS 27, Settings > Cellular shows app usage and lets you reset the phone’s statistics. Note the counter’s start date and time before resetting it. Phone statistics and carrier billing periods may differ, and resetting the phone does not change carrier usage or billing. Note each period and update time; do not treat phone totals as an invoice. Apple directs users to their carrier for the most accurate mobile-data total.
Add expected updates, game downloads, and first cloud sync separately if they did not occur during the test. Do not count phone usage twice if it is already included.

Also record the phone’s battery level at the start and end, whether you charged it, and whether it still has the charge you need before leaving home. A phone that must remain at home, drains too quickly, or needs to stay plugged in at an inconvenient spot may not suit your routine. Battery use varies by device condition and usage, so base this decision on your own test. If a temperature warning appears, stop using the phone, turn it off, move it out of direct sunlight to a cooler place, and wait for it to cool. Heat can slow or stop charging and reduce wireless performance. Keep the phone in a ventilated place while using or charging it; do not cover it with bedding or pillows. Follow the current Apple safety guidance and do not ignore a temperature warning to keep tethering.

Decide what to do next

If the needed tasks work with data and battery to spare, keep the current plan and avoid an unnecessary contract. If data charges may rise, compare that amount with another option’s setup, device, monthly, and cancellation costs over the same period. If devices at home must remain connected while you leave, or normal tasks fail, compare fiber, a home router, and mobile Wi-Fi in the guide to choosing an internet connection.

If a condition is unclear, ask the carrier about data and charges, Apple or the device maker about phone steps, and the property manager about installed internet. Do not use an unknown condition as a fixed number in a cost comparison.

LINEMO’s cancellation-fee rules can depend on the contract date, application route, and plan at cancellation. For some new contracts from July 1, 2026, a request within 12 months may incur a fee. Check the current official notice and your contract; do not apply the example to every existing customer. The direction of migration exceptions matters: moving from LINEMO to SoftBank or Y!mobile is different from moving to LINEMO from those services.

Official sources (Japanese)

The Japanese source file records each reference’s scope and its own verification date. The sources below are in Japanese.