Troubleshoot SMS Not Delivering
Troubleshoot SMS Not Delivering
If your text messages are not reaching recipients, this guide walks through the most common causes and how to resolve each one.
Available on: All plans with SMS enabled
Common causes of SMS delivery failure
| Cause | How to identify | Fix |
|---|---|---|
| 10DLC not registered | Error message mentions unregistered campaign or brand | Complete 10DLC brand and campaign registration |
| Recipient opted out | Message log shows "Opted Out" status | Recipient must text START to your number to re-subscribe |
| Carrier filtering | Messages silently not delivered — no error in log | Review message content for spam-like language; register 10DLC |
| Character encoding issues | Special characters render incorrectly or message fails | Use GSM-7 compatible characters; avoid copy-pasting from Word |
| Number type restrictions | Toll-free number used for local-only campaigns | Use a local or 10DLC-registered number |
| Rate limits exceeded | Burst of messages followed by failures | Throttle sending; check your plan's messages-per-second limit |
Step 1: Verify 10DLC registration (US traffic)
All US A2P (Application-to-Person) messaging requires 10DLC registration. If your brand and campaign are not registered, carriers will block your messages.
- Go to Settings > SMS > 10DLC Registration.
- Confirm your Brand status is Approved.
- Confirm your Campaign status is Active.
- Verify the sending number is associated with an approved campaign.
If any of these are incomplete, see 10DLC Registration Steps.
Step 2: Check opt-out status
If a recipient previously replied STOP to your number, all future messages to that recipient are blocked automatically.
- Go to SMS > Conversations and search for the recipient's number.
- If the conversation shows an opt-out flag, the recipient must text START to your JustCall number to re-subscribe.
- You cannot manually override an opt-out — this is a carrier-level compliance requirement.
Step 3: Review message content
Carriers use automated filters to block messages that look like spam. Avoid:
- ALL CAPS messages
- Excessive use of links (especially URL shorteners)
- Phrases like "Free," "Act now," "Limited time" in bulk campaigns
- Messages without an opt-out instruction (required for marketing campaigns)
Step 4: Check character encoding
SMS messages use GSM-7 encoding (160 characters per segment). If your message includes non-GSM characters (smart quotes, em dashes, certain emojis), it switches to UCS-2 encoding, reducing the limit to 70 characters per segment. This can cause messages to be split or rejected.
Avoid copy-pasting text from Microsoft Word or Google Docs, which often inserts smart quotes and special dashes.
Step 5: Verify number type and rate limits
- Local numbers require 10DLC registration for A2P messaging.
- Toll-free numbers require toll-free verification.
- Short codes have the highest throughput but require separate registration.
Check your plan's SMS throughput limit at Settings > Account > Plan Details. If you are sending bulk campaigns, stagger delivery to stay within your per-second rate limit.