Twilio MMS messaging is a popular way to send media files, especially images, to end users in the U.S. and Canada. In addition to photos, Twilio MMS messaging also accepts numerous other file formats.

However, for customers who wish to send PDF files to recipients using MMS, there are some limitations to be aware of. It is especially important to note that some U.S. and Canadian mobile networks do not support receiving PDF files by long code MMS.

Read on for more details on short code as well as long code PDF support via MMS.

Short code MMS support for PDF files

Twilio short code numbers in the U.S. can be enabled for MMS in addition to SMS. If you are using a short code to send MMS messages in the United States, PDF files are well-supported by mobile carriers and should deliver successfully to users with modern smartphones.

Please note that PDF files are currently considered an "accepted" file type by Twilio. This means we will accept the file you submit to us and send it downstream to the mobile network, as long as it meets that network's size limit for media files. However, we will not resize or make other adjustments to the file itself for device compatibility. For this reason, it's important to ensure your PDF files are smaller than the maximum attachment size of the network you are sending toward. Currently, the mobile network with the smallest limit for short code MMS attachments is AT&T. AT&T's attachment size limits for short code MMS media is 600kb.

For complete details and per-carrier size limits, see Twilio Programmable SMS Supported File Types and Size Limits for MMS Media Messages and refer to the "Short code MMS attachment size" column of the size limit table for non-image files.

Long code MMS support for PDF files

The AT&T mobile network in the United States, as well as Fido, Rogers, and Telus in Canada do not support PDF attachments on MMS messages sent via long codes (standard 10-digit local numbers) toward subscribers on their networks.

For users on these mobile networks, a PDF file attachment on an MMS message will not reach the device. The user will receive the Body text of your message (if one was included), with the following text appended: "One or more of the message components have been deleted by MMS Adaptation. Either the message was too large or the components were unsuitable for your handset."

As of today, long code MMS messaging is considered a person-to-person (P2P) channel by most mobile networks in the U.S. and Canada. These mobile networks may choose to extend support to PDF files via long code MMS at a later date, when and if they introduce long code A2P messaging offerings similar to Verizon 10DLC. However, Twilio is not aware of any specific plans relating to PDF support via long code.

WhatsApp and other messaging channels

The above information is applicable to MMS messaging. Other messaging channels such as WhatsApp have different rules and file type support. PDF files are an officially supported media attachment type for WhatsApp users. For information about media messaging with WhatsApp on Twilio, see Sending and Receiving Media with WhatsApp Messaging on Twilio.