## Send a message in a chat **post** `/v1/chats/{chat}/messages` Sends a reply on an existing chat's unchanged sending number. The chat supplies the customer and sender; this operation never creates, moves, repins or fails over a conversation. Acceptance and refusal semantics are otherwise identical to `POST /v1/messages`. ### Path Parameters - `chat: string` ### Header Parameters - `"Idempotency-Key": optional string` ### Body Parameters - `parts: array of object { body, type, preview_url } or object { kind, type, caption, 4 more } or object { language, name, type, 3 more } or 8 more` The message content — sendable parts only, at least one. **One outbound part per request.** Each request has its own acceptance result and optional idempotency key. Each accepted request maps to one native channel message with its own identifier, delivery outcome and charge evidence. A request carrying more than one part is refused with HTTP 422 (`multiple_parts_not_available`); the API neither fans it out nor offers an atomic batch. Separate requests are independent, and no cross-request delivery or receipt order is promised. - `Text object { body, type, preview_url }` A plain text message. - `body: string` The message text. URLs render as tappable links. - `type: "text"` - `"text"` - `preview_url: optional boolean` Render a preview card for the first URL in body. Defaults to false. - `Media object { kind, type, caption, 4 more }` A media message — image, video, audio, document, or sticker. The two identifiers are distinct namespaces: inbound media carries the channel's transient media_id; outbound media carries our durable upload_ref from POST /v1/media. - `kind: "image" or "video" or "audio" or 2 more` Which kind of media this is. Captions apply to image, video and document only; filename applies to document only. - `"image"` - `"video"` - `"audio"` - `"document"` - `"sticker"` - `type: "media"` - `"media"` - `caption: optional string` Caption rendered with the media. Image, video and document only — a caption on an audio or sticker part is rejected, never dropped. - `filename: optional string` Display filename. Documents only — a filename on any other kind is rejected, never dropped. - `media_id: optional string` Inbound only: the channel's transient media identifier. It expires after seven days and is never an outbound address; an outbound value is rejected with a pointer to media_id and upload_ref as the remedy. - `upload_ref: optional string` Outbound only: our durable handle returned by POST /v1/media. Handles visibly begin upload. and are reusable within the account and test/live partition that created them. - `url: optional string` Response only: stable attachment download URL requiring the account Bearer key on every request. Pending capture returns 409 with Retry-After; retained bytes expire 30 days after server receipt. Historical unbound messages omit this field. Never accepted on sends. - `Template object { language, name, type, 3 more }` An approved message template — the one part type sendable outside an open customer service window. name and language identify the approved template; parameters fills its named placeholders. Authentication templates use this same generic part unchanged: the channel supplies the OTP substitution, so do not invent or pass a code parameter unless the template's published parameter schema explicitly names one. Every sendable template is registered and approved ahead of the send and publishes its own parameter schema — a send referencing an unknown template, a missing or unknown parameter, or a value that breaks the template's rules is rejected with a 422 naming the exact field. - `language: string` The template's language-and-locale code, e.g. en_US. - `name: string` The approved template's name. Lowercase letters, digits and underscores only. - `type: "template"` - `"template"` - `cards: optional array of object { card_index, kind, upload_ref, 2 more }` Per-card values for an approved media-card carousel. The approved template's send_schema provides structural bounds and an x-rule listing the exact card order, media kind, named body values, and dynamic button slots enforced by runtime L2 validation. Omit for non-carousel templates. - `card_index: number` - `kind: "image" or "video"` - `"image"` - `"video"` - `upload_ref: string` A durable handle returned by POST /v1/media. It is resolved within this key's account and partition, then consumed into a transient channel media identifier only at delivery. - `buttons: optional array of object { index, payload, type }` - `index: number` - `payload: string` - `type: "quick_reply" or "url"` - `"quick_reply"` - `"url"` - `parameters: optional unknown` Named values for this card's body placeholders. - `header: optional object { kind, upload_ref }` The uploaded media used for this approved template's media header. Omit unless this template's send_schema requires it. - `kind: "image" or "video" or "document"` - `"image"` - `"video"` - `"document"` - `upload_ref: string` A durable handle returned by POST /v1/media. - `parameters: optional unknown` Named values for the template's placeholders. The shape is per-template: each registered template publishes its own parameter schema — hand THAT schema to your model when composing a specific template. Omit for templates with no placeholders. - `InteractiveList object { body, button, sections, 3 more }` An interactive list message: body text plus a button that opens a sectioned list of selectable rows. The customer's selection arrives as an inbound interactive_reply part with kind list_reply, carrying the chosen row's id. - `body: string` The message body. - `button: string` Label of the button that opens the list. - `sections: array of object { rows, title }` The list's sections, each holding selectable rows. At most 10 rows in total across ALL sections combined — not 10 per section. - `rows: array of object { id, title, description }` This section's rows. The 10-row limit is on the TOTAL across all sections, so a second section reduces what this one may hold. - `id: string` Your identifier for the row — echoed back as the interactive_reply's id. - `title: string` The row's visible title. - `description: optional string` Secondary text under the title. - `title: optional string` Section title. Required when the list has more than one section. - `type: "interactive_list"` - `"interactive_list"` - `footer: optional string` Footer text below the body. - `header: optional string` Header text above the body. - `InteractiveButtons object { body, buttons, type, 3 more }` An interactive reply-buttons message: body text plus up to three tappable buttons. The customer's tap arrives as an inbound interactive_reply part with kind button_reply, carrying the tapped button's id. - `body: string` The message body. - `buttons: array of object { id, title }` The tappable buttons — at most three. - `id: string` Your identifier for the button — echoed back as the interactive_reply's id. - `title: string` The button's visible label. - `type: "interactive_buttons"` - `"interactive_buttons"` - `footer: optional string` Footer text below the body. - `header: optional string` Header text above the body. - `media_header: optional object { kind, upload_ref }` Uploaded image, video, or document above the body. Use either header or media_header, never both. - `kind: "image" or "video" or "document"` - `"image"` - `"video"` - `"document"` - `upload_ref: string` A durable handle returned by POST /v1/media. - `InteractiveCtaURL object { body, display_text, type, 3 more }` An interactive call-to-action message: body text plus one button that opens a URL. - `body: string` The message body. - `display_text: string` The button's visible label. - `type: "interactive_cta_url"` - `"interactive_cta_url"` - `url: string` The URL the button opens. Must be absolute, with an http or https scheme. - `footer: optional string` Footer text below the body. - `header: optional string` Header text above the body. - `LocationRequest object { body, type }` Asks the customer to share a location. The response arrives as a location part. - `body: string` Prompt shown above the send-location button. - `type: "location_request"` - `"location_request"` - `AddressRequest object { body, country, type }` Reserved for asking an eligible customer in India to submit a structured address. Sending this part is not available until business and customer eligibility can be verified at acceptance. Address responses already arrive as address_reply parts. - `body: string` Prompt shown above the address form. - `country: "IN"` ISO country code. Structured address requests are currently available only in India. - `"IN"` - `type: "address_request"` - `"address_request"` - `Contacts object { contacts, type }` One or more contact cards. - `contacts: array of object { name, addresses, birthday, 4 more }` The contact cards to send. The channel permits far more; this API caps a message at five, because a message carrying hundreds of cards is a mistake rather than a use case. - `name: object { formatted_name, first_name, last_name, 3 more }` - `formatted_name: string` The contact's full display name. - `first_name: optional string` - `last_name: optional string` - `middle_name: optional string` - `prefix: optional string` - `suffix: optional string` - `addresses: optional array of object { city, country, country_code, 4 more }` - `city: optional string` - `country: optional string` - `country_code: optional string` - `kind: optional string` A label for the address, e.g. WORK, HOME. - `state: optional string` - `street: optional string` - `zip: optional string` - `birthday: optional string` The contact's birthday as YYYY-MM-DD. - `emails: optional array of object { email, kind }` - `email: string` - `kind: optional string` A label for the address, e.g. WORK, HOME. - `org: optional object { company, department, title }` - `company: optional string` - `department: optional string` - `title: optional string` - `phones: optional array of object { phone, kind, messaging_id }` - `phone: string` The phone number, ideally in +E.164 form. - `kind: optional string` A label for the number, e.g. CELL, MAIN, WORK, HOME. - `messaging_id: optional string` The contact's messaging-account identifier on this channel, when known — makes the card openable in the messaging app. - `urls: optional array of object { url, kind }` - `url: string` - `kind: optional string` A label for the URL, e.g. WORK, HOME. - `type: "contacts"` - `"contacts"` - `Location object { latitude, longitude, type, 2 more }` A location pin. - `latitude: number` Latitude in decimal degrees. - `longitude: number` Longitude in decimal degrees. - `type: "location"` - `"location"` - `address: optional string` The place's address, shown under the name. - `name: optional string` The place's name, shown on the pin. - `Reaction object { emoji, type, channel_message_id, message_id }` An emoji reaction to an earlier message in the chat. The two identifiers are distinct namespaces: inbound reactions carry the channel's opaque channel_message_id; outbound reactions will carry this API's message_id once sending them becomes available. - `emoji: string` A single emoji. Send an empty string to remove a previous reaction to the same message. - `type: "reaction"` - `"reaction"` - `channel_message_id: optional string` Inbound only: the channel's opaque identifier for the message being reacted to. Match it literally to Message.channel_message_id in the chat transcript; never parse it or compare it with Message.id. - `message_id: optional string` Outbound only: this API's Message.id for the message being reacted to. Outbound reactions are not available yet; when they land, the API resolves this identifier into the channel namespace before sending. - `reply_to_message_id: optional string` Our opaque `Message.id` for an earlier message in this same chat. - `send_at: optional string` RESERVED — scheduled sends are not yet available. Any value is refused. ### Returns - `AcceptedMessage object { id, chat_id, created_at, 7 more }` An accepted send: the message, plus how its sending number was chosen. - `id: string` This API's message id. Once outbound reactions are available, put this value in their `message_id`. Mark-as-read targets the latest unread inbound message in a chat, so it takes the chat id. - `chat_id: string` The chat this message belongs to. - `created_at: string` - `direction: "inbound" or "outbound"` `inbound` (from the customer) or `outbound` (sent by you). - `"inbound"` - `"outbound"` - `parts: array of object { body, type, preview_url } or object { kind, type, caption, 4 more } or object { language, name, type, 3 more } or 14 more` The message content — sendable parts, plus the inbound-only types on inbound messages. Every message carries at least one part. - `Text object { body, type, preview_url }` A plain text message. - `body: string` The message text. URLs render as tappable links. - `type: "text"` - `"text"` - `preview_url: optional boolean` Render a preview card for the first URL in body. Defaults to false. - `Media object { kind, type, caption, 4 more }` A media message — image, video, audio, document, or sticker. The two identifiers are distinct namespaces: inbound media carries the channel's transient media_id; outbound media carries our durable upload_ref from POST /v1/media. - `kind: "image" or "video" or "audio" or 2 more` Which kind of media this is. Captions apply to image, video and document only; filename applies to document only. - `"image"` - `"video"` - `"audio"` - `"document"` - `"sticker"` - `type: "media"` - `"media"` - `caption: optional string` Caption rendered with the media. Image, video and document only — a caption on an audio or sticker part is rejected, never dropped. - `filename: optional string` Display filename. Documents only — a filename on any other kind is rejected, never dropped. - `media_id: optional string` Inbound only: the channel's transient media identifier. It expires after seven days and is never an outbound address; an outbound value is rejected with a pointer to media_id and upload_ref as the remedy. - `upload_ref: optional string` Outbound only: our durable handle returned by POST /v1/media. Handles visibly begin upload. and are reusable within the account and test/live partition that created them. - `url: optional string` Response only: stable attachment download URL requiring the account Bearer key on every request. Pending capture returns 409 with Retry-After; retained bytes expire 30 days after server receipt. Historical unbound messages omit this field. Never accepted on sends. - `Template object { language, name, type, 3 more }` An approved message template — the one part type sendable outside an open customer service window. name and language identify the approved template; parameters fills its named placeholders. Authentication templates use this same generic part unchanged: the channel supplies the OTP substitution, so do not invent or pass a code parameter unless the template's published parameter schema explicitly names one. Every sendable template is registered and approved ahead of the send and publishes its own parameter schema — a send referencing an unknown template, a missing or unknown parameter, or a value that breaks the template's rules is rejected with a 422 naming the exact field. - `language: string` The template's language-and-locale code, e.g. en_US. - `name: string` The approved template's name. Lowercase letters, digits and underscores only. - `type: "template"` - `"template"` - `cards: optional array of object { card_index, kind, upload_ref, 2 more }` Per-card values for an approved media-card carousel. The approved template's send_schema provides structural bounds and an x-rule listing the exact card order, media kind, named body values, and dynamic button slots enforced by runtime L2 validation. Omit for non-carousel templates. - `card_index: number` - `kind: "image" or "video"` - `"image"` - `"video"` - `upload_ref: string` A durable handle returned by POST /v1/media. It is resolved within this key's account and partition, then consumed into a transient channel media identifier only at delivery. - `buttons: optional array of object { index, payload, type }` - `index: number` - `payload: string` - `type: "quick_reply" or "url"` - `"quick_reply"` - `"url"` - `parameters: optional unknown` Named values for this card's body placeholders. - `header: optional object { kind, upload_ref }` The uploaded media used for this approved template's media header. Omit unless this template's send_schema requires it. - `kind: "image" or "video" or "document"` - `"image"` - `"video"` - `"document"` - `upload_ref: string` A durable handle returned by POST /v1/media. - `parameters: optional unknown` Named values for the template's placeholders. The shape is per-template: each registered template publishes its own parameter schema — hand THAT schema to your model when composing a specific template. Omit for templates with no placeholders. - `InteractiveList object { body, button, sections, 3 more }` An interactive list message: body text plus a button that opens a sectioned list of selectable rows. The customer's selection arrives as an inbound interactive_reply part with kind list_reply, carrying the chosen row's id. - `body: string` The message body. - `button: string` Label of the button that opens the list. - `sections: array of object { rows, title }` The list's sections, each holding selectable rows. At most 10 rows in total across ALL sections combined — not 10 per section. - `rows: array of object { id, title, description }` This section's rows. The 10-row limit is on the TOTAL across all sections, so a second section reduces what this one may hold. - `id: string` Your identifier for the row — echoed back as the interactive_reply's id. - `title: string` The row's visible title. - `description: optional string` Secondary text under the title. - `title: optional string` Section title. Required when the list has more than one section. - `type: "interactive_list"` - `"interactive_list"` - `footer: optional string` Footer text below the body. - `header: optional string` Header text above the body. - `InteractiveButtons object { body, buttons, type, 3 more }` An interactive reply-buttons message: body text plus up to three tappable buttons. The customer's tap arrives as an inbound interactive_reply part with kind button_reply, carrying the tapped button's id. - `body: string` The message body. - `buttons: array of object { id, title }` The tappable buttons — at most three. - `id: string` Your identifier for the button — echoed back as the interactive_reply's id. - `title: string` The button's visible label. - `type: "interactive_buttons"` - `"interactive_buttons"` - `footer: optional string` Footer text below the body. - `header: optional string` Header text above the body. - `media_header: optional object { kind, upload_ref }` Uploaded image, video, or document above the body. Use either header or media_header, never both. - `kind: "image" or "video" or "document"` - `"image"` - `"video"` - `"document"` - `upload_ref: string` A durable handle returned by POST /v1/media. - `InteractiveCtaURL object { body, display_text, type, 3 more }` An interactive call-to-action message: body text plus one button that opens a URL. - `body: string` The message body. - `display_text: string` The button's visible label. - `type: "interactive_cta_url"` - `"interactive_cta_url"` - `url: string` The URL the button opens. Must be absolute, with an http or https scheme. - `footer: optional string` Footer text below the body. - `header: optional string` Header text above the body. - `LocationRequest object { body, type }` Asks the customer to share a location. The response arrives as a location part. - `body: string` Prompt shown above the send-location button. - `type: "location_request"` - `"location_request"` - `AddressRequest object { body, country, type }` Reserved for asking an eligible customer in India to submit a structured address. Sending this part is not available until business and customer eligibility can be verified at acceptance. Address responses already arrive as address_reply parts. - `body: string` Prompt shown above the address form. - `country: "IN"` ISO country code. Structured address requests are currently available only in India. - `"IN"` - `type: "address_request"` - `"address_request"` - `Contacts object { contacts, type }` One or more contact cards. - `contacts: array of object { name, addresses, birthday, 4 more }` The contact cards to send. The channel permits far more; this API caps a message at five, because a message carrying hundreds of cards is a mistake rather than a use case. - `name: object { formatted_name, first_name, last_name, 3 more }` - `formatted_name: string` The contact's full display name. - `first_name: optional string` - `last_name: optional string` - `middle_name: optional string` - `prefix: optional string` - `suffix: optional string` - `addresses: optional array of object { city, country, country_code, 4 more }` - `city: optional string` - `country: optional string` - `country_code: optional string` - `kind: optional string` A label for the address, e.g. WORK, HOME. - `state: optional string` - `street: optional string` - `zip: optional string` - `birthday: optional string` The contact's birthday as YYYY-MM-DD. - `emails: optional array of object { email, kind }` - `email: string` - `kind: optional string` A label for the address, e.g. WORK, HOME. - `org: optional object { company, department, title }` - `company: optional string` - `department: optional string` - `title: optional string` - `phones: optional array of object { phone, kind, messaging_id }` - `phone: string` The phone number, ideally in +E.164 form. - `kind: optional string` A label for the number, e.g. CELL, MAIN, WORK, HOME. - `messaging_id: optional string` The contact's messaging-account identifier on this channel, when known — makes the card openable in the messaging app. - `urls: optional array of object { url, kind }` - `url: string` - `kind: optional string` A label for the URL, e.g. WORK, HOME. - `type: "contacts"` - `"contacts"` - `Location object { latitude, longitude, type, 2 more }` A location pin. - `latitude: number` Latitude in decimal degrees. - `longitude: number` Longitude in decimal degrees. - `type: "location"` - `"location"` - `address: optional string` The place's address, shown under the name. - `name: optional string` The place's name, shown on the pin. - `Reaction object { emoji, type, channel_message_id, message_id }` An emoji reaction to an earlier message in the chat. The two identifiers are distinct namespaces: inbound reactions carry the channel's opaque channel_message_id; outbound reactions will carry this API's message_id once sending them becomes available. - `emoji: string` A single emoji. Send an empty string to remove a previous reaction to the same message. - `type: "reaction"` - `"reaction"` - `channel_message_id: optional string` Inbound only: the channel's opaque identifier for the message being reacted to. Match it literally to Message.channel_message_id in the chat transcript; never parse it or compare it with Message.id. - `message_id: optional string` Outbound only: this API's Message.id for the message being reacted to. Outbound reactions are not available yet; when they land, the API resolves this identifier into the channel namespace before sending. - `InteractiveReply object { id, kind, title, 2 more }` Inbound only — never sendable. The customer's selection from an interactive_list (kind list_reply) or interactive_buttons (kind button_reply) message, carrying the id you assigned to the chosen row or button. - `id: string` The id you assigned to the chosen row or button. - `kind: "list_reply" or "button_reply"` Which interactive message kind was answered. - `"list_reply"` - `"button_reply"` - `title: string` The chosen row's or button's visible title. - `type: "interactive_reply"` - `"interactive_reply"` - `description: optional string` The chosen list row's secondary text, when it had one. - `AddressReply object { type, values, saved_address_id }` Inbound only: the structured values submitted in response to an address request. - `type: "address_reply"` - `"address_reply"` - `values: object { address, building_name, city, 8 more }` - `address: optional string` - `building_name: optional string` - `city: optional string` - `floor_number: optional string` - `house_number: optional string` - `landmark_area: optional string` - `name: optional string` - `phone_number: optional string` - `pin_code: optional string` - `state: optional string` - `tower_number: optional string` - `saved_address_id: optional string` Identifier of the selected saved address, when one was selected. - `Order object { catalog_id, items, type, text }` Inbound only — never sendable. An order the customer placed from a product catalog. - `catalog_id: string` The catalog the ordered items belong to. - `items: array of object { currency, price, product_retailer_id, quantity }` The ordered items. - `currency: string` ISO 4217 currency code for price. - `price: number` The per-item price at order time. - `product_retailer_id: string` Your identifier for the product, as registered in the catalog. - `quantity: number` - `type: "order"` - `"order"` - `text: optional string` Free text the customer attached to the order, when any. - `Referral object { type, body, click_id, 7 more }` Inbound only — never sendable. The ad or post context a customer's first message arrived from (for example an ad whose call to action opens a chat). A referral also opens a free-entry-point customer window — see the chat's customer_window. - `type: "referral"` - `"referral"` - `body: optional string` The ad's body text at click time. - `click_id: optional string` The click identifier assigned by the ad platform, for attribution. - `headline: optional string` The ad's headline at click time. - `image_url: optional string` URL of the ad's image creative, when media_kind is image. - `media_kind: optional string` The ad creative's media kind, e.g. image or video. - `source_id: optional string` The ad or post id. - `source_kind: optional string` What the source was, e.g. ad or post. - `source_url: optional string` The URL of the ad or post the customer came from. - `video_url: optional string` URL of the ad's video creative, when media_kind is video. - `System object { body, type, event }` Inbound only — never sendable. A system event in the chat, such as the customer changing their number. New event kinds appear over time; body is always present and human-readable. - `body: string` Human-readable description of the system event. - `type: "system"` - `"system"` - `event: optional string` The system event's kind, when the channel identifies one. New kinds appear over time — treat unknown values as informational. - `Unsupported object { raw, type, kind }` Inbound only — never sendable. A message kind this API does not yet type natively, carried as a typed passthrough: raw holds the channel payload, so a new message kind is never a black box or a silent drop. Native part types for popular kinds are added over time; this part is the compatibility guarantee in the meantime. - `raw: unknown` The channel payload — any JSON value: object, array, string, number, boolean, or null. Deliberately unconstrained, because the whole point of this part is to carry a shape this API does not yet know. For rows written by API version 1.3.0 or later, object member order, number formatting and duplicated members survive storage and read-back. The canonical encoder may compact insignificant whitespace before storage. Rows written before API version 1.3.0 retain normalized JSON only: member order and number formatting may differ, and only the last duplicated member survives. - `type: "unsupported"` - `"unsupported"` - `kind: optional string` The channel's name for the message kind, when it declares one. - `status: string` The message's delivery state as last reported. Inbound messages read `received`: they arrived, and no delivery of ours ran. A message you sent starts `accepted` and moves through `sent`, `delivered` and `read` as the channel reports them, with `failed` as the definitive negative outcome. `unknown` means exactly that: the send is INDETERMINATE and we decline to guess. It is NOT terminal — an indeterminate send is never re-sent, and it resolves to `sent`, `delivered`, `read` or `failed` when the channel's own report arrives — so keep observing rather than treating it as an outcome. States are reported asynchronously on the chat's event sequence, and the set grows additively: treat a value you do not recognise as "no information" rather than failing on it. Retention of this published status follows the chat transcript policy: there is no scheduled pruning during beta, but there is no fixed minimum availability guarantee. The present absence of a scheduled age-based sweep is not a promise of indefinite availability. UNDER A `sk_test_` KEY THESE ARE SIMULATED. A test-key send is reported `sent` and then `delivered` within milliseconds, every time; `delivered` there means a simulator accepted it, not that a device received it. Live delivery can lag by hours, can never report `delivered` at all, and can fail after the channel accepted the message — so do not calibrate timeouts or "delivered means it arrived" logic against a test key. - `channel_message_id: optional string` The channel's opaque identifier for this message, when the channel has assigned one. Match an inbound reaction's `channel_message_id` to this field literally; never parse it or compare it with `id`. It is absent while an accepted outbound message has not yet received a channel identifier. - `failure: optional object { code, message }` Why a failed message failed, when we have a reason worth publishing. Present only on `status` `failed`, and not on every one of those: not every channel refusal has a reason in the published vocabulary, so a message that failed on the wire may carry no `failure` at all. Its absence means "no published reason", never "no reason". `status` stays the thing to branch on. This is additive detail beside it, so an integration written before this field existed still sees a terminal `failed` and behaves exactly as it did. - `code: string` The specific reason. `sender_deregistered` — the number this message was going out from is no longer a registered sending number, and the message never left. This is terminal: it is not a pause and it does not clear, so retrying the same message cannot succeed and that conversation is over. Reach this customer by starting a new one on another of your numbers with a template, exactly as you would any customer whose 24-hour window has closed; `GET /v1/chats` shows which number each conversation uses. You are not billed for a message that failed this way. `quality_hold_expired` — this marketing message remained held by an automatic safety control on its sending line for ten minutes and was not sent. This is terminal: retrying the same message cannot succeed on that conversation. Send marketing from another of your numbers with a template, or contact support about the sending line. You are not billed for a message that failed this way. - `message: string` Human-readable, written for a person reading it. Do not branch on it. - `from: optional string` The number this message left by, or arrived on, in E.164 (leading `+`). Every message in one conversation carries the same value — a conversation never moves to another number. Absent only if the number is no longer one of yours. - `from_selection: optional object { reason }` Present only when this service chose the sending number for you — that is, when you omitted `from`. A send that named `from` omits this rather than reporting a choice nobody made. - `reason: string` Why this number was used. Exactly one of: - `reused_active_chat` — this customer already had a conversation and it continues on the same number. - `new_best_number` — there was no existing conversation, so the best available number was chosen. Like every other vocabulary here it is a plain string that may grow additively; treat a value you do not recognise as "chosen for you". ### Example ```http curl https://whatsapp.messages.api.linqapp.com/v1/chats/$CHAT/messages \ -H 'Content-Type: application/json' \ -H "Authorization: Bearer $LINQ_WHATSAPP_API_KEY" \ -d '{ "parts": [ { "body": "body", "type": "text" } ] }' ``` #### Response ```json { "id": "id", "chat_id": "chat_id", "created_at": "2019-12-27T18:11:19.117Z", "direction": "inbound", "parts": [ { "body": "body", "type": "text", "preview_url": true } ], "status": "status", "channel_message_id": "channel_message_id", "failure": { "code": "code", "message": "message" }, "from": "from", "from_selection": { "reason": "reason" } } ```