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LINE Official Account: Behaviour, Messages, and Constraints

This is the working reference for two-way conversation messaging on the LINE Official Account channel, line. It covers how the channel addresses a recipient, the consent that has to exist before you can address one, how LINE counts what you send, and then one complete request body per supported content type, each followed by its field explanations and its real constraints.

The line channel supports no templates. If you need a pre-approved structured notification, that is a different product: see LINE Official Notification (LON).

LOA Behaviour​

Three things decide the shape of an LOA integration: the identifier you address a recipient with, the consent that must exist before that identifier ever reaches you, and the sub-account the send is authenticated against. For the objects that sit underneath an Official Account and the channel type value that names each LINE product inside a payload, see The Technical Building Blocks and Channel Type Values.

Identifying a LINE Recipient​

This is the single biggest difference between LINE and 8x8's phone-number channels. LINE users have no phone number that you can address, so LINE issues an opaque user ID instead.

  • user.channelUserId is the field you populate when sending on the LINE Official Account channel. Use it instead of msisdn to address the recipient.
  • Format: the LINE Platform issues user IDs as a string matching the regular expression U[0-9a-f]{32}. That is the letter U followed by exactly 32 lowercase hexadecimal characters.
  • Scope: the user ID is issued per provider. The same person has a different user ID under a different provider, so a user ID you obtained elsewhere is not portable into your LINE integration.
  • The same field name carries it back to you. user.channelUserId is also where the LINE user ID arrives on inbound message webhooks, so one field name covers both directions. channelUserId also appears in delivery receipts from this channel, which report Accepted and Sent statuses. See Delivery Receipts.
  • user.msisdn is absent for LINE on everything you receive. The inbound webhook contract states that msisdn is left out for channels where users have no phone number, and names LINE as the example. When a user field has no value, it is left out of the JSON entirely rather than sent as null. There is also no reason to send msisdn on an LOA request: see the Message API Library for the send payloads.

How you obtain a channelUserId​

LINE sends the user ID to the bot server in a webhook when a user adds your LINE Official Account as a friend (a follow event) or sends it a message. On 8x8, that arrives at your registered callback URL as an inbound message webhook with the LINE user ID in user.channelUserId.

LINE also publishes endpoints that return the user IDs of all of your friends, and of all members of a group or multi-person chat. Both are available only to Verified or Premium accounts, and neither is exposed through the 8x8 API.

Key Takeaway: You cannot send a first message to a LINE user from a phone number. The user must add your LINE Official Account as a friend and produce an inbound event first. Capture and store the channelUserId from that event, because it is the only address you will have for that user.

To access a LINE user's profile information, the user must have consented to allow access to it. Users of LINE for iOS and LINE for Android consent when they begin using LINE. Users who have only ever used LINE for PC cannot consent, and since April 2020 it is no longer possible to create an account on LINE for PC.

If a user has not consented, their profile information is omitted from the webhook event, which means the webhook contains no user ID at all. Practically, that user is unaddressable: they can add your Official Account as a friend and even send you messages, but you have no identifier to send back to.

Other causes of a missing profile, per LINE, are that the user never added your Official Account as a friend, blocked it after adding it, or left the group chat it belongs to.

Sub-accounts and Authentication​

The line channel is provisioned on its own 8x8 sub-account and authenticated with that sub-account's own bearer token.

  • Its own sub-account. A LINE integration requires a new sub-account. It cannot be an existing SMS sub-account, and it is not the sub-account that serves LINE Official Notification. The {subAccountId} in the send URL is the LOA one.
  • Its own bearer token. The API key that authenticates an LOA send does not authenticate a LON send. Generate it in the 8x8 Connect portal, scoped to the LOA sub-account.
  • Its own recipient key. /messages on the line channel takes user.channelUserId. LON's /lon endpoint takes user.msisdn instead.

One LINE Official Account can serve both products at the same time, but each product needs its own 8x8 sub-account. See The LINE Official Account for the account-level view, and LINE Official Notification (LON) for LON's side of the split.

Important: Confirm with your account manager which of these sub-accounts you have been provisioned, and which API key belongs to which. Sending a LINE Official Notification payload to /messages, or a LINE user ID to /lon, will not work.

Message Counting and Plan Quotas​

Your LINE Official Account sits on a LINE subscription plan with a monthly allowance of free messages. How LINE counts against that allowance is LINE's rule, not 8x8's, and it surprises people:

  • LINE counts by recipient, not by message object. A single request containing four message objects sent to a chatroom of five people counts as five messages. The number of message objects in a request does not affect the count.
  • Messages that cannot be received are not counted. If you send to a user who blocked your Official Account, or to a user ID that does not exist, that message is not counted.
  • Not all sending methods count. LINE counts push, multicast, broadcast, and narrowcast messages toward the plan allowance. Reply messages are not counted. The 8x8 send request has no reply-token field, so an 8x8 LINE send cannot be a LINE reply message.
  • The hard stop is your total monthly ceiling, not the free allowance on its own. LINE describes this under the heading "When you exceed the limit of free messages", but what it actually enforces is the limit of messages that can be sent in a month: once you exceed it, LINE returns an error response and the message is not sent. Plans that support additional messages let you send past the free allowance and pay per additional message, up to a maximum number of additional messages that you configure in LINE Official Account Manager. Your real ceiling on those plans is the free allowance plus that configured maximum. Plans that do not support additional messages have no such extension, so for them the free allowance is the ceiling.

Note

Plan tiers, allowances, and additional-message pricing are LINE's, they are purchased in LINE Official Account Manager, and they vary by country. LINE publishes them itself: see LINE Official Account (Thailand). Talk to your 8x8 account manager about sizing the plan for your expected volume.

Supported Types at a Glance​

Content typeOutboundInbound
TextYesYes
ImageYesYes
VideoYesYes
AudioYesYes
LocationYesYes
FileNoYes

Important: The asymmetry on File is real and it catches people out. A LINE user can send your Official Account a file, and you will receive it as an inbound File message. There is no outbound File type on this channel, so you cannot send one back.

For the full inbound contract, including the envelope, the field-by-field description, and the 24-hour expiry on inbound media URLs, see Inbound Messages.

For one complete request body per supported type, with screenshots and LINE's real limits, see Message API Library.

For Developers:

Important Concepts:

  • The LINE Ecosystem and Account Model - Account types, Verified Account review, Premium ID, what a single Official Account can serve, and the Messaging API channel and channel type values underneath it

Cross-channel References:

External: