Troubleshooting SMS delivery issues

Updated 14 March 2026 · 75 views

If your SMS messages aren't arriving as expected, this guide will help you identify and resolve the most common issues.

Check your message status first

Start by checking the delivery status of your message on the History page. The status tells you exactly what happened to each message after it was sent.

See Understanding message delivery statuses for a full explanation of each status, or Viewing and exporting message history for help navigating the History page.

Message stuck on "Sent"

A Sent status means the message has been submitted to the mobile network but delivery hasn't been confirmed yet. This usually happens when the recipient's phone is switched off or out of reception range.

The network will continue retrying delivery. Once the phone comes back online, the status will update to Delivered. If the retry period expires (usually 24–48 hours), the status will change to Not Delivered.

No action is needed — just wait for the status to update.

Message shows "Not Delivered"

Not Delivered means the mobile network was unable to deliver the message. Common causes include:

  • The recipient's phone number has been disconnected or is no longer active.
  • The phone was switched off or out of range for longer than the network's retry period.
  • The number is on a network that rejected the message.

If you're unsure whether a number is still active, try calling it. If the call doesn't connect at all, the number may be disconnected.

See Understanding message delivery statuses for more detail on what each status means.

Message shows "Delivered" but the recipient says they didn't get it

If a message has a Delivered status, it was successfully delivered to the recipient's phone. However, the phone itself may have filtered the message into a spam or junk folder.

Both iPhone and Android devices have built-in spam filtering that can sometimes catch legitimate messages. Ask the recipient to:

  1. Check their spam, junk, or filtered messages folder in their messaging app.
  2. On iPhone, check Settings > Messages > Unknown & Spam for filtered messages.
  3. On Android, open the messaging app and look for a Spam & blocked section.

See Why was my SMS marked as spam on a phone? for more information on how phone-level spam filtering works and how to reduce the chance of your messages being filtered.

Messages are sending slowly

Delivery speed depends on several factors, including the size of your recipient list and network conditions.

  • A single message is typically delivered within seconds.
  • Batch sends to large lists are processed sequentially and may take longer depending on the list size.

See How long will it take for my messages to be delivered? for expected delivery timeframes.

Scheduled message didn't send

If a scheduled message didn't send at the expected time, check the following:

  • Timezone — Scheduled times use the timezone set in your account. Make sure this matches your local timezone.

See Scheduling an SMS message for more details on how scheduling works.

Message used more credits than expected

Each SMS can contain up to 160 standard characters. Messages that exceed this limit are split into multiple parts, and each part uses one credit. Common causes of unexpected credit usage include:

  • Unicode characters — Emojis, smart quotes (curly quotes), and characters from non-Latin alphabets switch the message to Unicode encoding, which reduces the per-part limit to 70 characters.
  • Pasting from Word or email — This often introduces hidden Unicode characters like smart quotes or special dashes.

See Understanding SMS parts and Unicode for a full explanation of how message length and encoding affect credit usage.

Can't send to a number

If you're unable to send to a specific number, check these common causes:

Recipients can't reply

Whether recipients can reply depends on the type of sender you used:

  • Shared number — Replies are supported and are delivered to your inbox.
  • Dedicated number — Replies are supported and are delivered to your inbox.
  • Business name (custom sender ID) — Recipients cannot reply to messages sent from a business name, as there is no phone number to reply to.

If you need two-way messaging, use a dedicated or shared number as your sender.

See Choosing a sender for a comparison of sender types, and Two-way SMS basics for more on how replies work.

Still need help?

If you've worked through the steps above and are still experiencing issues, contact our support team:

  • Email: hello@mobilemessage.com.au
  • Live chat: Use the chat widget on any page

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