SMS Attachment Size Limits

SMS carriers have attachment file size limitations to prevent deliverability issues and to make sure that their servers are not overloaded with hefty file sizes while millions of people around the world use their services to send SMS.

SMS

We support up to 10 attachments, as long as the total size of the message body text and all attachments is less than 5 MB.

NOTE: To send attachments, your Twilio phone number must be MMS-enabled.

Carriers also have limits. The average is 300kb-600kb and can go up to 3.5MB for tier 1 providers (AT&T/Verizon, etc.)

Here are the Carrier Attachment Size limits for some common US Carriers:

The file sizes above will generally be passed along to the wireless carriers. However, due to differences in handsets, file types, and transcoding, we recommend you send attachments no larger than 500KB to ensure the best chance of delivery.

These image file types are supported:

• jpeg
• png
• Gif

Twilio automatically transcodes image file attachments in supported formats (jpeg, png, and gif) to ensure compatibility with destination devices, but it does not transcode or resize any other media types.

For non-image file types (e.g., files other than jpeg, png, or gif), the attachment size limit varies by carrier and is generally smaller than for image files. For instance, AT&T long code MMS allows up to 1.0 MB, but Toll-Free MMS is limited to 0.6 MB.

To avoid potential delivery failures, it is recommended to keep attachments no larger than 600KB when sending non-image files or using specific carriers like AT&T.

There is no size limit for incoming MMS to your Twilio numbers, but Twilio will only display the first 10 media attachments if more than 10 are received, even though the Twilio Console will show all media attachments associated with the message.

If the total size of your message body text and attachments exceeds 5 MB, your MMS message request will fail, and any message (including body text and media) larger than 5 MB will not be delivered.

Other media types like MP4 files are supported as MMS attachments but cannot be directly sent as SMS attachments. MP4 files will be sent as MMS, and if recorded in the mobile app, a link will be generated for the recipient to view the video.

As of May 2021, there is an issue with Toll-Free MMS file size support; for these numbers, you must ensure that any attachments (including images) are 600kb or smaller.

FAQs

1. Can I send attachments with SMS using Twilio?
   • Yes, you can send attachments using Twilio, but your phone number must be MMS-enabled. You can include up to 10 attachments, provided the total size of the message body text and attachments is less than 5 MB.
2. What are the size limitations for MMS attachments?
   • The size limits vary by carrier, typically ranging from 300KB to 600KB, and up to 3.5MB for tier 1 providers like AT&T and Verizon. For non-image files, the limits can be lower; for example, AT&T allows up to 1.0 MB for long code MMS but only 0.6 MB for Toll-Free MMS. It’s recommended to keep non-image attachments under 600KB to avoid delivery issues.
3. What file types are supported for MMS, and does Twilio transcode these files?
   • Twilio supports image files in jpeg, png, and gif formats and automatically transcodes these for compatibility with destination devices. Other media types, such as MP4 files, are also supported but are not transcoded or resized by Twilio. Non-image files often have more restrictive size limits depending on the carrier.
4. Can I receive MMS messages on my Twilio number, and are there any limitations?
   • Yes, there is no size limit for incoming MMS messages to your Twilio numbers. However, Twilio will only display the first 10 media attachments if more than 10 are received, even though all media attachments will appear in the Twilio Console.
5. What happens if the total size of my MMS exceeds 5 MB?
   • If the total size of your MMS message (including body text and attachments) exceeds 5 MB, the message request will fail, and the message will not be delivered. It’s crucial to ensure that the total size remains within the allowed limit to avoid delivery failures.