SMS & MMS

SMS and MMS messaging delivers open rates above 90%, making text messaging one of the highest-performing communication channels in the platform. The system supports full two-way messaging with text-only SMS and multimedia MMS for images, videos, and files. Every message flows into the unified Conversations inbox alongside email, live chat, and social channels, giving your team a single workspace for all customer communication.

What SMS & MMS Does

The platform handles business text messaging through local 10-digit long code (10DLC) numbers, toll-free numbers, and short codes. SMS messages are limited to 160 characters per segment using standard encoding, while MMS messages support up to 10 media files with a 5 MB total size limit.

Core capabilities:

Two-way conversations with automatic contact creation
Manual messaging from the Conversations inbox with templates
Automated messaging through workflow triggers
Broadcast campaigns to segmented audiences
Compliance automation with opt-out handling and STOP keyword processing
Real-time delivery tracking with error codes for troubleshooting

A2P 10DLC registration is required for local numbers in the United States. This process verifies your brand and campaign with carriers to ensure deliverability. Navigate to Settings > Phone Numbers > Trust Center to complete brand and campaign registration before sending messages. Approval typically takes 1 to 5 business days.

Message segmentation determines cost. SMS segments are 160 characters with standard encoding or 70 characters when emojis trigger UCS-2 encoding. MMS messages carry higher per-segment and carrier fees. Cost formula: (Segments x Per-Segment Cost) + (Segments x Carrier Fees).

Key Configuration Options

Phone number setup: Navigate to Settings > Phone Numbers, click Add Number, and choose local (10DLC), toll-free, or short code. Local numbers are the most common choice for business messaging in the US and Canada.

Messaging compliance: Navigate to Settings > Phone Numbers > Messaging > Messaging Compliance. Enable Add opt-out message (e.g., “Reply STOP to unsubscribe”), Add sender information (your business name), and Periodic Opt-Out to automatically re-add compliance language at configurable intervals (1 to 60 days). These settings ensure TCPA and CTIA compliance.

Campaign registration: After brand registration, submit a Campaign Registration in the Trust Center describing your use case, sample messages, and opt-in method. Include opt-out language in at least one sample message. Common rejection reasons include mismatched brand details, missing opt-out language, and pre-checked opt-in boxes.

Opt-in methods: The platform supports web forms (optional consent checkbox), verbal consent (with transcript), paper forms (hosted screenshot), text-to-join (keyword trigger), and QR codes. Marketing and non-marketing consent must use separate checkboxes.

Power Features

Group chat: Create multi-participant SMS threads from the Conversations panel. All replies appear in the same thread, making it easy to coordinate with multiple stakeholders on a single project or family.

Template library: Navigate to Marketing > Templates to create SMS templates with personalization tokens like {{contact.first_name}} and {{contact.company}}. Templates are accessible directly from the Conversations inbox when composing messages.

Workflow automation: Use the Send SMS and Send MMS actions in workflows for appointment reminders, lead follow-ups, review requests, payment reminders, and re-engagement campaigns. Add triggers like form submission, appointment booked, or tag added.

Broadcast campaigns: Navigate to Marketing > SMS Marketing to send one-to-many messages. Select audiences using smart lists, tags, or filters, then schedule for immediate or future delivery.

Automatic compliance: The platform automatically processes STOP and START keywords, adds DND status for opted-out contacts, and appends compliance language at configurable intervals. No manual intervention required.

Pro Tips

Get explicit opt-in before sending any message. Never add contacts to SMS campaigns without documented consent. This protects deliverability and keeps you legally compliant.
Keep messages under 160 characters to minimize segment costs. Every additional segment multiplies your expense. Use the Twilio Segment Calculator to check counts before finalizing templates.
Paste text as plain text (Cmd+Shift+V on Mac, Ctrl+Shift+V on Windows) to avoid hidden characters from word processors that inflate segment counts.
Monitor your opt-out rate and keep it below 2%. A high opt-out rate signals that your messaging frequency or content needs adjustment.
Warm up new numbers gradually. Start with low volume and increase over days. The platform enforces a ramp-up model for new sub-accounts to protect deliverability.

Common Questions

How do I know if my message was delivered?

Check the conversation thread in the Conversations inbox. Delivered messages show a delivery confirmation. Failed messages display an error code you can use to troubleshoot.

What is the difference between SMS and MMS pricing?

MMS messages cost more per segment than SMS. An MMS also carries higher carrier fees. For example, a 5-segment MMS costs roughly $0.15 compared to about $0.07 for a 5-segment SMS.

What happens when a contact replies STOP?

The platform automatically opts the contact out of SMS communication and adds DND status for the SMS channel. The contact must text START to re-enable messaging.

Why are my messages being filtered or blocked?

Common causes include missing A2P 10DLC registration, high complaint rates, sending to landlines, content that triggers spam filters, or exceeding your daily sending limit. Check the Conversations view for specific error codes.

What file types can I send via MMS?

The platform supports images (JPEG, PNG, GIF), videos (MP4), and other common file types. Total attachment size must be under 5 MB. Larger files are automatically converted to a shareable link and sent via SMS instead.