LINE dominates messaging in Japan, Taiwan, and Thailand. If you do business with anyone in those markets, LINE is almost certainly how they prefer to talk — email is treated as a slow, formal channel, and phone calls are reserved for emergencies. But LINE is also the most quietly weird of the major messengers, because it deliberately hides phone numbers.
Phone number vs LINE ID vs display name
Every LINE account is registered with a phone number, but that number is invisible to other users by default. To find someone on LINE, you use one of three identifiers:
- Phone number — only works if the other person has enabled "Allow others to add me by phone number" and you have the same number saved locally. Off by default in Japan.
- LINE ID — a self-chosen public handle, 4–20 characters, letters and numbers, permanent once set. Looks like
@tanaka_tokyoorcoffee_shop_kyoto. - QR code — every account generates a personal QR you can screenshot and share. Scanning it in the LINE app opens a friend-add screen instantly.
The display name — the "Yuki 👋" or "Kenta S." you see at the top of a chat — is cosmetic. Two accounts can share the same display name; the ID is what's unique.
Why phone number lookup often fails
LINE was built in the aftermath of the 2011 Tōhoku earthquake, when Japanese phone networks went down and NHN Japan wanted a way for colleagues to reach each other without depending on carriers. Because it launched in a market where phone numbers were treated as private (Japanese business cards traditionally hide mobile numbers), LINE's default privacy settings assume you don't want to be found by number.
In practice this means: if you type someone's Japanese phone number into LINE and hope to add them, roughly nine times out of ten nothing will happen. The account exists, but it's shielded.
How to add someone on LINE — the reliable ways
- Ask for their LINE ID. On business cards it's usually printed with the LINE app icon next to it. Type it into LINE's "Add friends → Search by ID" screen.
- Scan their QR code. This is the default in-person method in Japan and Taiwan. Both phones open LINE, one taps QR, the other shows theirs, done.
- Have them tap a share URL. LINE generates a personal
https://line.me/ti/p/…URL you can send by email or SMS. Tapping it on a phone with LINE installed opens the friend-add screen. - Shake phones together. LINE has a "Shake it!" feature that finds nearby LINE users by phone motion. Rarely used but fun.
How Ringlink handles LINE
Because phone-number lookup is unreliable on LINE, Ringlink treats it as a "best-effort" launcher. Tapping the LINE button on a phone number:
- Opens LINE with a search query for that number if the app supports it on your OS, or
- Opens the LINE app's Add Friends screen where you can paste the person's LINE ID directly, if you have it.
If you already know the LINE ID, save yourself a step and enter it in Ringlink's Username lookup field. We build the correct line:// deep link that jumps straight to their profile.
Business accounts (LINE Official)
Shops, brands, and news outlets use LINE Official Accounts, which broadcast to followers instead of holding one-on-one chats. Their IDs start with @ (e.g. @starbucks_jp). Anyone can search and follow them. If someone hands you a card with @-prefixed ID, they mean the official account, not a personal one.
The takeaway
In LINE-heavy markets, always collect the LINE ID or QR code. A phone number alone is often useless. Ringlink prioritizes the LINE button when it detects a Japan or Taiwan country code, but the fastest path is still: ask for the ID, tap the LINE tile, paste, done.