FAQs about MMS at Telnyx
Here you will find frequently asked questions about sending and receiving MMS, answered.
Telnyx Engineering avatar
Written by Telnyx Engineering
Updated over a week ago

What are the supported file types for MMS?

  • text/plain

  • text/vcard

  • image/jpeg

  • image/png

  • image/gif

  • video/3gpp

  • video/mp4

What should the “content-type” of my stored media be, and how does it differ case-by-case?

Content type should equal to one of the above. It can also be application/octet-stream - in that case we try to guess the content type based on the media binary.

Are media files for outbound messages cached within Telnyx? If so, for how long?

Yes, media files for outbound messages are cached within Telnyx for an hour. Changing the media url -- like adding a spurious query parameter -- will invalidate the cache.

How can I secure my media for outbound messages to only be read by Telnyx?

Whitelist and

Does MMS work between countries (ie USA to Brazil)?

No, we don't have this capability yet.

How do MMS DLRs function?

There are three kinds of DLRs. Normally we expect each MMS to generate all of the following:

  1. Internal DLR that is generated when we successfully submit MMS to the terminating carriers. This DLR changes the status of the stored MDR to “sent”.

  2. MM4_forward.RES - we get this when the terminating carriers pass our MMS message to the destination carrier. This DLR changes the status of the stored MDR to “delivered”.

  3. MM4_delivery_report.REQ - we (sometimes) get it from the destination carrier and it indicates what happened to the message - usually it means it was delivered to the handset.

How does MMS differ when sending from a Toll-Free Number?

MMS can be sent from a Toll-Free Number, at a rate limit of 6 MMS/min.

How does MMS differ when sending from a Short-Code?

We need a short code provisioned with our terminating carriers and the campaign must be approved by all major carriers.

How can I send a long-text message as a MMS (with no attachments)?

Set the parameter as “type=MMS”.

What is the maximum file size of a single attachment?

Total attachment size must be less than 1 MB. Ideally, it should be 1MB minus 100KB to give some space for encoding overhead.

What about total message size with multiple attachments?

Total message size is capped at 1 MB, and no more than 10 media_urls are allowed.

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