10 Reasons Your Bulk SMS Is Not Delivering And What To Do

Did you send out your bulk SMS campaign and it doesn’t seem to be delivered?

You are probably in one of those greatly annoying positions where after taking your time to compose a truly warm and heartfelt bulk SMS message for your subscribers. 

Then click. . . You hit send with a broad smile on your face and go your way to attend to other businesses. You come back twenty minutes later and aarrghh! Your bulk SMS didn’t send or it was sent to only a handful of people.

Your bulk SMS report is showing a poor delivery rate. Meaning over half of your subscribers didn’t get your warm message! How did this happen? you ask yourself. . . You grind your teeth not knowing if you should smash your phone or curl up on your bed in frustration.

Now, relax . . . Take a bottle of Schweppes, sit back and see why your messages didn’t send properly and what you can do to fix it. 


1. Scam/Spam Words:

When the body of your message or sender ID contains scam or spam words, your SMS will be blacklisted by the GSM operators and will not be shown to the intended recipients. Some examples of spam or scam words are “congrat, euro, lottery, you have won, survey, your number has been selected, MTN, GTB, NOKIA” e.t.c.

2. Invalid/Blocked Phone number:

Sometimes it’s not even your fault, your subscriber’s number is just blocked. This means that they might have subscribed to DND(Do not disturb). The only way around this is to use a more expensive routing channel to bypass the DND.

It might also be that the subscriber's phone number is incorrect.

3. Recipient’s Phone Number Switched Off For Long:

Each SMS has a validity period so much that when it expires, the message disappears. When your recipient's phone number is switched off for that long, the message will disappear and they won’t get it when they switch their phones back on.

4. Subscriber Out of Network Coverage Area:

Once your subscriber goes out of network coverage for too long, the message you sent will actually expire.

5. Using Cheap Routes:

Some bulk SMS providers promise very cheap pricing on the SMS packages. What they do is use illegal routes, like the SIM Boxes and grey routes to connect to the GSM at very low costs. As these routes have been blacklisted, any service provider still using them will get unpredictable results, normally the customers will have to suffer for it. 

Don’t be too hung up on “Cheap”.

6. Recipient’s Inbox Full/Message Application Frozen:

Your recipient's inbox could be full. You might have forgotten about this. In this case, the message comes in but because the inbox is full, the recipient will not be able to access it until they delete some messages to make space for it. 

In the same vein, the message application might be frozen or malfunctioning. This happens on smartphones. In this case, the recipient would have to restart their phones or find other ways to fix the issue before they can get your message.

7. Message Length:

The number of characters an SMS can contain for each country varies. It’s 160 for the USA but 157 for Brazil. If your message exceeds this limit, your message will get rejected unless your service provider automatically splits it into different messages. 

You need to be careful here as your link can get broken. So double-check before you send out that SMS.

8. Error with the GSM Operator:

Yes, GSM operators do have errors from time to time. There might be an overloaded queue at the SMS center of your mobile operator, delaying the time or bouncing back you SMS. 

9. Encoding: 

Encoding issues might also be the reason your SMS is not sent. At a basic level, encoding determines the possible combination of characters for which characters can be sent. Typically, messages are sent using either Unicode, which allows for 70 characters, or using the global standard GSM 3.38 which allows 160 characters.

Different GSM operators in different countries require different encoding. Some won’t allow messages that are written with Unicode, while others will deliver the message incorrectly. 

When sending to a new country, always attempt to send in plain text (accents can sometimes show up incorrectly) as opposed to Unicode, and always check the Country Specific Guidelines to make sure you aren't missing any important information.

10. Error with Bulk SMS Provider: 

Finally, I am sorry, but maybe you might be using a pretty bad bulk SMS provider. Sometimes, all your problems can be caused by your bulk SMS provider. Check all of the above and cross them out. If it continues, it’s probably caused by your bulk SMS service provider.


1. Review your contacts often to regularly filter unresponsive numbers off your list. 

2. Offer double opt-in into your subscriber list as this is a great way to ensure that your bulk SMS gets down to your subscriber's inbox. 

3. Make sure your messages do not contain spam-related words and content. If any, eliminate them all. 

4. Don’t send bulk SMS all at once or too fast. Share the quota into two or more batches. 

You certainly need to work with one of the best. By best I mean the platform that gives you the best service, all-around, and to every country. Choose a platform that offers instant SMS delivery, delivery reporting in real-time, low SMS cost, and responsive customer support.

Cheap Global SMS is a leading bulk SMS provider to all countries with instant SMS delivery and reporting in real-time, at about the cheapest SMS rates worldwide.

If you have any questions or comments, we would love to hear from you. Please send them in the comment section.

DATE: Thu, 21st Oct. 2021 5:47pm

TAGS: Bulk Sms

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