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Overview

OpenPhone’s text messaging supports both SMS and MMS messages with rich features including AI-suggested responses, file attachments, and multimedia content. Send pictures, videos, documents, and GIFs to communicate effectively with customers and team members.

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Sending messages

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Basic text messages

Character limits:
  • Single SMS: 160 characters maximum. If you send a longer text, your recipients will not notice this limit as modern devices will reassamble the message for the reader.
  • Extended messages: Up to 1,600 characters (split into segments)
  • Unicode/Emoji messages: 70 characters per segment
Messages longer than 160 characters are automatically split into segments of 153 characters each and reassembled by the recipient’s device.
Messages exceeding 1,600 characters will fail to send. Break long content into multiple messages.

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Multimedia messaging (MMS)

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Sending pictures and attachments

  1. Click the 📎 icon next to “Write a message”
  2. Upload your image or file
  3. Add your message text and send
Attaching an image in OpenPhone web interface

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File size and image limits

Attachment limits:
  • Maximum file size: 5MB per message
  • Images per message: Up to 10 images
  • Supported formats: JPEG, PNG, GIF, PDF, and other common file types

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Carrier-specific MMS limits

Different carriers have varying size limits for receiving MMS: US/Canadian local numbers:
  • AT&T: 0.6MB
  • T-Mobile: 1.5MB
  • Verizon: 0.675MB
Toll-free numbers: 0.6MB standard limit
For best compatibility, keep attachments under 600KB when unsure of the recipient’s carrier.

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Picture quality

OpenPhone automatically resizes images under 5MB that exceed receiving carrier limits. For best picture quality when the recipient’s carrier is unknown, send images under 600KB.

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Supported content types

You can send various types of content through OpenPhone:
  • Pictures (MMS): JPEG, PNG, and other image formats
  • Videos: Video files within size limits
  • GIFs: Use GIPHY integration by typing ”/” in message field
  • Documents: Spreadsheets, PDFs, and other file types
  • Contacts: Share contact information
  • Reactions: Emoji reactions to messages

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AI-suggested responses

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How AI responses work

OpenPhone uses AI to suggest 2-3 relevant replies based on conversation context. Available on all platforms (web, desktop, iOS, Android) for all users.

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Using AI suggestions

  1. Basic suggestions: Type /AI in any conversation to get context-based response options
  2. Custom prompts: Type /AI followed by specific instructions
AI message response suggestions in OpenPhone
Example prompt: “/AI Create a short, friendly text that confirms a customer’s appointment on Monday at 9 am.”
AI prompt example for generating custom responses
Save useful AI-generated responses as snippets for future reuse.

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Message management

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Saving and storing messages

Messages are automatically saved when you mark conversations as “done”:
  1. Mark conversation as Done
  2. Access saved messages using the Done filter
  3. Messages stored indefinitely unless manually deleted
Done filter for accessing saved messages
If subscription is cancelled, message data is only guaranteed for 14 days. Export data before cancellation if needed.

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Message limitations

Cannot unsend messages: Unlike peer-to-peer platforms, SMS messages sent through carrier networks cannot be recalled once delivered. Bulk image download: Images must be downloaded individually - bulk download is not currently available. Character limit failures: Messages exceeding 1,600 characters will fail with an error message.
Failed message due to character limit

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Troubleshooting