Have you run into trouble sending SMS messages in Campaigns or Automation? Continue reading this article to learn more about the most common troubleshooting scenarios with the SMS channel.
SMS Message Not Received
If your contacts aren't receiving SMS campaigns or automation messages. Check the following possible 4 reasons:
1. Contact's Phone Number Format
The phone number must be in international format with a country code. Check the contact's profile:
Go to Audience → Contacts → Find the contact and open their contact profile.
Verify the phone number:
Includes country code (e.g., +1 for US, +44 for UK)
Contains no parentheses, dashes, or spaces (e.g., +11231234567, not (123) 123-4567)
Note: Omnisend automatically adds country codes for contacts who subscribe via checkout or signup forms. This issue usually only affects manually imported contacts.
2. SMS Channel Subscription Status
Contacts must be subscribed to the SMS channel to receive campaigns.
Check subscription status:
Go to Audience → Contacts → Find the contact and open their contact profile.
Look for the SMS channel status – It must show Subscribed (green badge).
Exception: Transactional automation (Order Confirmation, Shipping Confirmation, Order Cancellation) can send SMS to non-subscribed contacts in the EU and other countries (except the USA). See the full list of workflows that send to non-subscribed contacts.
3. Automation Settings
If you're using automation with multiple message channels (SMS + Email), enable the "Pass non-opted-in contact to next workflow step" option in every message block. This ensures that if a contact isn't subscribed to SMS, they'll receive the email message instead.
Go to Automations → Select your workflow
Click the message block → Enable "Pass non-opted-in contact to next workflow step" (on the right-hand menu).
Click Update.
Example: If your contact isn't subscribed to SMS, they'll automatically receive the email message if their email subscription status is Subscribed.
4. Message Length (Carrier Blocking)
Mobile carriers may block messages that are too long. The allowed length depends on the carrier's settings, but we strongly recommend keeping messages to 1–2 SMS splits maximum.
Check message length:
In the SMS editor, go to the Preview section.
Switch between US/CA preview and non-US preview.
Check the character count and number of SMS splits.
Note: US/CA recipients have longer opt-out instructions ("Reply STOP to unsubscribe"), so their messages may be longer than non-US recipients. Learn how SMS character counting works.
SMS Not Delivered to the Contact (Country Restrictions)
Particular countries have limitations on when SMS can be delivered. During these timelines, we will pause your SMS and will resend it afterward.
Armenia:
Monday - Friday - No SMS delivered between 9:00 p.m. and 9:00 a.m.
Saturday - No SMS delivered before 12:00 p.m. (midday) or after 6:00 p.m.
Sunday - No SMS delivered at all.
Transactional traffic can be sent anytime (Transactional SMS is for order confirmation, order cancellation, and shipping confirmation automations).
France: Carriers only accept delivery between 8:00 a.m. and 8:00 p.m. local time, Monday - Saturday. All SMS sent outside these hours will be rejected.
India: No SMS delivered between 9:00 p.m. and 10:00 a.m. IST for end recipients who registered with the Do Not Disturb Service (DND). This means promotional SMS can only be delivered between 10:00 a.m. and 9:00 p.m. IST.
Jordan: Promotional messages are not delivered after 9:00 p.m. Amman time (GMT + 3:00).
Saudi Arabia: Promotional or marketing SMS is allowed only between 8:00 a.m. and 10:00 p.m. Saudi Arabia time (GMT+03:00).
United Arab Emirates: Effective immediately, all international promotional SMS traffic to the United Arab Emirates is prohibited by mobile network operators. This restriction applies universally, impacting ALL service providers, including Omnisend. Only local promotional traffic is permitted, subject to end users having a registered entity in the UAE and completing the mandatory registration with local authorities. Compliance with this regulation is essential, as sending international promotional traffic via SMS to the UAE is now impossible. Adjust your strategies accordingly to navigate this change.
SMS Delivery to the UK
If you're sending SMS messages to the UK for the first time, you may experience temporary delivery delays. These should resolve within 1-2 days as the system adjusts.
Best practices for a smooth start:
Start small – Instead of sending a large campaign right away, begin with just a few contacts.
Stick to the same Sender Name – Avoid changing it to ensure faster approval.
Keep sending as usual – Delivery should improve automatically within a couple of days.
💡 Why the delay?
The delay is related to Sender ID (SID) registration. When you send messages to the UK for the first time, our SMS provider receives the request and begins the SID registration process. This usually takes around 24 business hours.
Sender's Name Not Showing
Certain countries don't support custom sender names. The US, Canada, and some other countries require messages to be sent from a dedicated phone number instead of a sender name.
Check if your country supports sender names: SMS Sender's Name – Supported Countries
💡 Solution: If your country doesn't support custom sender names, include your brand name at the beginning of your message so recipients recognize you:
Example: "Shopname: Flash sale – 50% off all shoes! Shop now: [link]"
SMS Message Counted as Multiple Messages
You sent an SMS campaign, but your credits were charged for 2 or more messages per contact instead of 1. This happens when your message exceeds 160 characters (or 70 characters if you use emojis or special characters).
Why This Happens
SMS has strict character limits:
Standard messages (GSM-7 encoding): 160 characters per SMS.
Messages with emojis or special characters (Unicode encoding): 70 characters per SMS.
If your message exceeds these limits, it's automatically split into multiple SMS messages. Recipients see one long message on their phone (due to concatenation), but you're charged for each SMS sent.
Common causes:
Auto-added compliance text – Unsubscribe links and opt-out instructions (e.g., "Reply STOP to unsubscribe") are added at send time and vary by recipient region:
US/CA recipients: Longer unsubscribe link (uses more characters);
Non-US recipients: Shorter opt-out text.
Emojis and special characters – These trigger Unicode encoding, which reduces the limit from 160 to 70 characters per SMS.
To avoid unexpected charges, keep your message under 140 characters to leave room for compliance text.
You can check the final segment count in the SMS credits step before sending.
⚠️ New Zealand has laws that require additional compliance text to be added to SMS messages containing links. This text is added automatically by Omnisend's backend at send time and cannot be disabled or previewed in the editor.
Because these additions are applied at send time and are not visible in the Omnisend editor, your message may exceed the 160-character limit and be counted as 2 SMS messages, increasing costs. Always account for approximately 25-30 additional characters when sending to New Zealand contacts.
Subscribers' Country is Not Recognized
If you upload contacts without country codes, Omnisend may recognize them as belonging to the wrong country and won't send the message. This issue only affects manually imported contacts.
How to resolve:
Add the country code to the phone numbers (e.g., +1 for US, +44 for UK).
💡 Excel tip: You can use the CONCATENATE function to quickly add country codes. See Microsoft's guide on combining text from cells.
Note: You don't need to delete the contacts before uploading the updated data. Omnisend will only update the information according to your latest import.
SMS Messages Sent to Email Unsubscribers
If you wish to send your SMS campaign to the contacts that are subscribed to both SMS and email channels, you need to create a segment with dual subscription rules:
Go to Audience → Create a segment → Create from scratch.
Set these filters:
Subscription status is subscribed to the Email channel, AND;
Subscription status is subscribed to the SMS channel.
3. Use that segment to send your SMS promotions.
Emojis and Special Characters Not Showing
Emojis and special characters (é, ñ, ç) may not display correctly because mobile carriers filter them during delivery. This is outside Omnisend's control.
How to Avoid Display Issues
Test your message – Send a test SMS to yourself before launching your campaign. If emojis don't display, remove them and use text alternatives (e.g., "SALE" instead of 🔥).
Use standard characters – Stick to letters (a-z, A-Z), numbers (0-9), and basic punctuation (, . ! ?).
Avoid accents – While Omnisend supports accents (é, ñ), carriers may strip them. Use "e" instead of "é" if delivery is critical.
⚠️ Important: Emojis trigger Unicode encoding, which reduces your character limit from 160 to 70 characters per SMS. This means you'll be charged for more messages. Learn more about character encoding.
Phone Number Not Collected from Abandoned Cart on Shopify
If you notice that phone numbers are not being captured from the Abandoned Cart checkout, check if you have Abandoned Cart automation enabled in your Omnisend account. Once enabled, phone numbers will be captured for future abandoned carts (not retroactively).
FAQ
My test SMS didn't arrive. How do I fix this?
Test SMS messages won't arrive if:
The phone number isn't in international format with country code (e.g., +1XXXXXXXXXX for US, no dashes or parentheses).
The test number isn't subscribed to SMS in Omnisend.
Quiet hours are enabled in Store Settings (messages delayed up to 24 hours).
Carrier spam filters block the message (even if it's just a test message, it should be of an actual campaign).
Test messages also consume SMS credits, so check your credit balance. If using US numbers, make sure your toll-free number is verified (required for US SMS delivery).
Try testing with a different phone number in international format to isolate the issue.
Why are my SMS credits disappearing faster than the number of campaigns I sent?
SMS credits are shared across all campaigns and active automations (abandoned cart, welcome series, product browse, etc.).
Check:
Active automation workflows with SMS blocks—these run in the background and send automatically when contacts meet trigger conditions
Test messages sent during campaign or automation setup (each test uses credits)
Message length—messages over 160 characters (or 70 with emojis/special characters) split into 2–3 segments per recipient, multiplying credit usage
To see where credits are going, review your Automation Reports for SMS sends in the selected time period.
Need more help? Reach out to [email protected] or via in-app chat. We are available 24/7.