Skip to main content
Contact support Service status Platform login
Deutsch Español Français
Sign in

Sending MMS (Multimedia messaging)

Updated

Some features are only available on particular plans or as paid add-ons and you can check inclusions on our pricing page.  If you have any other questions, contact support and we can review your plan and provide you with options, including to speak to one of our Customer Success team.

 

MMS (Multimedia Messaging Service) is an effective way to share visual information and increase message engagement using images, audio, video, PDFs, or contact cards.

Before you get started:

  • Account enablement: Sending MMS requires the feature to be enabled on your account. MMS is charged at a higher rate than standard SMS.
  • Receiving MMS: While there is no fee to receive inbound MMS messages, your account must have an active dedicated number capable of receiving MMS.
  • Platform access: MMS campaigns must be sent via the Sinch Engage web platform (MMS sending is not currently supported through the mobile app).

How to Send an MMS in Sinch Engage

  1. Open the Composer: In the left navigation menu, go to Messaging > New message and select the Attachment message (MMS) tab.

  2. Upload Your File: Drag and drop your media file or browse to upload. (See the Regional Specifications & Supported Formats section below for regional size limits and accepted extensions).

  3. Add a Subject Line (Optional): Enter a brief subject line for your message. You can also insert personalization tags (such as First name or Location).

  4. Draft Your Message Content: Enter your text body in the message content box. You can use personalization tags or leverage the built-in AI assistant to help refine your copy.

    Subject and message content fields screenshot

  5. Review and Send: Once your preview looks correct, click Send Now (or schedule the message for a later time).

MMS Specifications by Region | Overview

File size thresholds, supported media types, and video support vary depending on carrier networks in each destination country.

Summary Comparison

Specification Australia (AU) United States (US) Other Destinations / International
Overall Size Limit Up to 1 MB (1,000 KB) per message (combined attachments + text) Carrier & number dependent:
• Standard / 10DLC: ~740 KB – 1 MB (up to 2.2 MB on T-Mobile)
• Short Code: ~1 MB – 2.1 MB (up to 50 MB upload if transcoding is active)		 Subject to local carrier support (typically 300 KB – 450 KB)
Images JPEG, PNG, GIF JPEG, PNG, GIF (up to 1,000 KB without transcoding; up to 3,000 KB with transcoding) JPEG, PNG, GIF
Video Attachments Supported (.mp4, .3gp) Supported (.mp4 / 3GP; up to 1,000 KB binary without transcoding) Not supported as direct attachments (use hosted links)
Audio Attachments Supported (.mp3, .wav, .3gp) Supported (.mp3, .wav, .3gp; up to 1,000 KB without transcoding) Not supported
Documents & Contacts PDF, vCard (.vcf), Calendar (.ics) PDF, vCard (.vcf), Objects PDF, vCard (.vcf)
Subject Line Up to 80 characters Recommended under 80 characters Recommended under 80 characters
Body Text Limit Up to 5,000 characters per slide Up to 5,000 characters Standard MMS character limits

MMS Specifications by Region | Details

Australia 

For messages delivered across Australian mobile carriers (Telstra, Optus, and Vodafone):

File Formats & Recommendations

  • Images:
    • Recommended: .jpg, .jpeg, .png
    • Supported: .gif
    • Note: .webp is not universally supported across all Australian carrier handsets. We strongly recommend converting .webp images to JPEG or PNG before sending.
  • Video:
    • Recommended: .mp4 (encoded with H.264 and AAC audio)
    • Supported: .3gp
    • Unsupported formats: .mpg, .wmv, and .avi will be delivered by the network, but the recipient's default device player may fail to render or play the file. Always use MP4.
  • Audio:
    • Recommended: .mp3
    • Supported: .wav, .3gp (Note: Uncompressed .wav files consume file size quickly; MP3 is preferred).
  • Documents, Contacts & Calendar:
    • Supported: .pdf (preferred), .vcf (vCard), .ics (iCalendar).

Australia Sender ID Requirements

  • MMS in Australia is currently supported using standard long numbers (virtual numbers).
  • Verify that your specific sender number has MMS sending capabilities enabled prior to launching your campaign.
United States

MMS message limits in the United States vary according to message content, sender type (Short Code, 10DLC, Toll-Free), and carrier networks.

1. Upload Size Limits (By Transcoding Feature)

Transcoding automatically optimizes media files so they meet recipient carrier specifications:

  • Accounts With Transcoding: (Supported on Short Code senders)
    • Images: Up to 3,000 KB
    • GIFs: Up to 1,024 KB
    • Audio: Up to 10,000 KB
    • Video: Up to 50,000 KB
    • Text: Up to 5,000 characters
    • MMS Objects: Up to 2,048 KB
  • Accounts Without Transcoding: (Applies to 10DLC, Toll-Free, and non-transcoded Short Code senders)
    • Images: Up to 1,000 KB
    • Audio: Up to 1,000 KB
    • Video: Up to 1,000 KB

2. Carrier Maximum Size Limits (US Networks)

When transcoding is not active, final message sizes delivered across mobile operators must comply with individual carrier limits:

US 10DLC (Local Long Code)
Operator Binary File Size Limit Base64 Encoded Limit
AT&T ~741 KB (~758,784 bytes) 1.0 MB
T-Mobile USA ~2.2 MB (~2,306,867 bytes) 3.1 MB
Verizon Wireless ~879 KB (~900,000 bytes) 1.2 MB
U.S. Cellular ~1.46 MB (~1,530,843 bytes) 2.0 MB
US Short Code
Operator Binary File Size Limit Base64 Encoded Limit
AT&T ~1.0 MB (~1,050,000 bytes) 1.4 MB
T-Mobile USA ~2.1 MB (~2,100,000 bytes) 2.8 MB
Verizon Wireless ~1.26 MB (~1,260,000 bytes) 1.68 MB
U.S. Cellular ~1.46 MB (~1,530,843 bytes) 2.0 MB

Important notes for US sending:

  • Base64 encoding increases the raw file size by approximately 1.37× of the original binary file.
  • Carrier MMSC thresholds are determined by individual network operators and may change. For maximum deliverability across all US carriers without transcoding, keeping binary media files under 700 KB is recommended.
  • For full file type details, refer to the Sinch Supported MMS File Types Guide.
Sending Videos outside US & AU

Due to international carrier constraints outside of Australia and the United States, direct video file attachments (.mp4, .mov) cannot be attached to MMS messages.

To share video content with audiences in other countries:

  1. Host your video on an accessible streaming platform (such as YouTube, Vimeo, or your own website).
  2. Insert a short link directly into your message body text.
  3. Consider attaching an animated GIF or high-resolution JPEG image as a visual preview to encourage link clicks.

Best Practices for MMS Deliverability & Rendering

To ensure your multimedia content looks great on all handsets and operating systems:

  • Optimize file weight: Even where larger allowances are permitted, keeping files compact ensures faster delivery and smoother downloads for end-users on slower mobile connections.
  • Video clips: Keep video attachments short (typically 5 to 15 seconds) and adjust resolution (e.g., 720p or lower) and bitrate to comfortably fit within carrier size limits.
  • Keep subject lines concise: While optional, subject lines should remain under 80 characters to avoid being truncated on smaller mobile screens.
  • Handset compatibility: Content rendering is governed by the recipient's handset model, OS version (iOS vs. Android), and default messaging app. Standard formats (.jpg, .png, .mp3, .mp4, .pdf) offer the highest cross-platform compatibility.

Related to

Related articles