Our business messaging API supports sending and receiving Viber for Business messages.

Being able to send Viber messages requires requesting access via the Channels portal. Without onboarding with Viber via the portal, you can not make use of this part of the API. Please be aware that Viber needs to verify the legitimacy of your business and your rationale for usage.

Fact Sheet

Feature	Support	Remarks
delivery notification	yes	Occurs when your message is delivered to the Viber platform. Delivery notifications are sent to the status report webhooks.
text messages	yes	The maximum length of a message is 1000 characters. Text formatting like bold, italics, monospace and strikethrough text are supported (see below).
media	yes	Media URL attributes should end in the proper file extension. Only one media file is allowed per message; when sending multiple files, each file will be sent in its own message. When the linked media doesn't exist/can't be found, the message will not be sent at all.
media: images	yes	Maximum file size for an uploaded image is 200 MB. Supported formats: png, jpeg, jpg, gif.
media: audio	no
media: video	yes	Maximum file size for an uploaded video file is 200 MB. Maximum duration of the video can be up to 10 minutes. Supported formats: mp4. Server which host the video must include 'Content-Length' in response header.
media: document	yes	Maximum file size for an uploaded file is 200 MB. Supported formats: doc(x), xls(x), csv, pdf.
suggestion as button	yes	Only 1 button is possible
rich card	yes	Only 1 button is possible
OTP templates	yes	Predefined OTP templates, configurable with own variables.
carousel	yes	Number of items from 2 to 5. Each item can have a image with expected formats png, jpeg, jpg. Each item have two buttons ( one of them optional)
list	yes	Number of items from 2 to 5

Sending messages

Viber is one of the few channels which uses telephone numbers as recipients. This allows SMS to be used as a fallback delivery channel if the recipient doesn't have the Viber app installed on their mobile device.

Please note that when defining fallback text, it is affected by the maximum size limitations of SMS as described in the section on SMS multipart messaging.

Onboarding

Two-way messaging

Two-way messaging determines whether users can reply to your Viber messages. This setting is configured during onboarding and affects how your messages function.

Two-Way Enabled:

Users can reply to your messages
User replies are sent to your message URL webhook
You receive and can respond to user messages

Two-Way Disabled:

Users can't reply to your messages
One-way broadcast communication only

Important: Transactional and Promotional messaging work with two-way, either enabled or disabled.

Message categories

When you onboard to CM.com for Viber for Business, you will need to decide which message category you will be sending. This decision determines your pricing structure and what types of content you can send. Our system automatically selects the appropriate message type based on what you send. If you want to change your message category, please contact your account manager.

Important: If you try to send promotional messages while onboarded for transactional (or vice versa), your message will not be sent.

What you send	Rate category	Available for
Text only	Transactional	Transactional
Text only (marketing)	Promotional	Promotional
File/Document	Transactional	Transactional
List (2-5 items)	Transactional	Transactional
Image only	Promotional	Promotional
Image + Text	Promotional	Promotional
Image + Text + Button	Promotional	Promotional
Text + Button	Promotional	Promotional
Video	Promotional	Promotional
Carousel (2-5 cards)	Promotional	Promotional
OTP Templates	OTP (dedicated rate)	Transactional and promotional (has its own rate)
Country Specific Templates (RU/UA/BY)	Transactional	Transactional

Transactional

What are transactional Messages?

Transactional messages are essential business communications that provide important information to your users.

What you can send as Transactional:

Text: Simple text notifications without images or buttons
Files/Documents: PDF, DOC, DOCX, XLS, XLSX, CSV files (max 200 MB)
Lists: 2–5 items in a vertical list format for presenting options

Promotional

What are promotional messages?

Promotional messages are marketing and commercial communications designed to engage users, drive sales, and build brand awareness. These messages include rich media, interactive elements, and visual content.

What you can send as promotional:

Text: Simple text notifications without images or buttons
Images: Standalone images (PNG, JPEG, JPG, GIF - max 200 MB)
Image + Text: Visual content with description
Image + Text + Button: Rich cards with call-to-action
Text + Button: Simple call-to-action messages
Video: Video content (MP4 only, max 200 MB) with or without text/button
Carousels: 2-5 swipeable cards with images and buttons

Special categories

OTP (One-Time Password) Templates

What are OTP Templates?

OTP templates are pre-approved, ready-to-use templates specifically designed for sending verification codes and authentication messages. They have dedicated OTP pricing separate from transactional and promotional rates. Available for, both transactional and promotional accounts (has its own dedicated rate). More about OTP templates