---
title: "MMS: images, PDFs and media"
description: "Attach an image, PDF or short video in the SMS composer and K3X sends it as MMS. Limits and carrier quirks."
url: https://help.k3x.ai/en/articles/95-mms-images-pdfs-and-media
collection: "Email, Calls and SMS"
updated: 2026-10-04
language: en
---

# MMS: images, PDFs and media

Attach an image, PDF or short video in the SMS composer and K3X sends it as MMS. Limits and carrier quirks.

SMS carries text. MMS carries images, PDFs, audio, short video and contact cards. Attach a file in the SMS composer and K3X sends the message as MMS automatically. Your 10DLC or toll-free registration covers MMS too, so there is nothing extra to register.

## What you can send

-   **Images**: JPG, PNG, GIF. A photo of a quote, a screenshot, a product shot. Many carriers flatten animated GIFs to one frame.
    
-   **PDFs**: one-page quotes, signed agreements.
    
-   **Audio**: MP3, WAV, mostly for voice notes.
    
-   **Short video**: MP4. Keep it under roughly 30 seconds at standard quality or carriers reject it.
    
-   **vCards**: contact files. The recipient gets a one-tap "Add to Contacts" prompt.
    

## Size limits

Carrier limits vary, and K3X enforces conservative ones to protect delivery:

-   **Total payload: 5 MB.** K3X compresses images that are too large. Oversized PDFs are rejected with an error.
    
-   **Per file: 1 MB recommended.** Larger files are allowed but some carriers filter them.
    
-   **Message body: up to 1,600 characters**, longer than the 160 of SMS.
    

For anything over 1 MB, or when image quality matters, upload the file to the record's **Files** panel or a shared drive and text a link instead.

## How to attach

1.  Open a person or company and click the **SMS** chip. The composer docks in place.
    
2.  Click the attachment icon, pick a file, or drag it into the composer. You can also paste a screenshot from your clipboard.
    
3.  Check the preview. K3X shows the file size and notes if it compressed an image.
    
4.  Type a message body. A bare attachment with no text looks like spam to carriers and to people.
    
5.  Click **Send**. K3X routes it as MMS.
    

## Inbound MMS

When someone texts you a photo or file, K3X stores the attachment on the message in the record timeline under the **SMS** filter. Download it from there.

## Credits

MMS spends credits from your single pool in the Texting category, the same pool as SMS, calls, AI actions and data reveals. MMS costs more than SMS per message. There is no separate SMS balance. See **Settings → Billing** for current usage.

## Carrier and country support

-   **US and Canada:** full MMS support on the major carriers, inbound and outbound.
    
-   **UK, Australia, most of the EU:** technically supported but rarely used. Most people there expect WhatsApp or email for media. Send a link instead.
    
-   **Elsewhere:** support is spotty. Use a link.
    

## Compliance notes

-   MMS follows the same A2P 10DLC and toll-free rules as SMS. One registration covers both.
    
-   Carriers filter MMS more aggressively than SMS, especially an empty body with a stock marketing image. Always write a personal line.
    
-   Some recipients on basic plans cannot receive MMS or pay per message. For unknown recipients, a link is the safer default.
    

## Troubleshooting

-   **Sent but not received.** The recipient's carrier or plan dropped it. Resend as a link.
    
-   **Image looks blurry.** Compression. Send a link for full quality.
    
-   **PDF shows as "1 attachment" on iPhone.** Normal iOS behavior. The recipient taps to open.
    
-   **GIF stopped animating.** The carrier flattened it. Use a short MP4 or a link.
    

## Related

-   Send your first SMS
    
-   International SMS: what works and what does not
    
-   A2P 10DLC registration guide