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Top 5 Reasons Your SMS Isn’t Being Delivered

January 13, 2015 Published by

If you’re currently running a global SMS program, you’ve probably realized by now that the SMS industry has not been very transparent.  Each country and carrier has their own rules about what type of traffic is allowed and it is difficult to know the intricacies. Here I’ll address some of the main problems we encounter when helping people increase their message delivery.

Nexmo-Change1) Using Cheap Routes: The bulks SMS industry has long been plagued by shady characters and tactics used to maximize margins. Techniques such as SIM boxes and “grey” routes are illegitimate ways for businesses to connect to the telecom network for a very low cost. With sending bulk SMS, the general rule is that you get what you pay for. SIM boxes, due to their illegality, are shut down by carriers and lead to extremely unpredictable and unreliable message delivery.

For more information about the SMS industry from a customers perspective, check out this post by EngageSPARK.

Nexmo-Filter2) Filtered Content: If I asked you to think of a few obvious examples of countries with banned or filtered content, it would probably be easy for you to come up with a few like China or Saudi Arabia, where the government controls what information citizens are allowed to receive.

Aside from the government filtering certain types of content, there is also the issue of what the carriers will allow. In Japan, for example, if there is a URL in the body of the message then the message delivery will fail. Those messages are classified as illegal, and are either discarded completely or the part of the text that is illegal will be removed. Before starting an SMS initiative, we recommend taking a look at our Country Specific Features and Restrictions  to make sure you are set up for obtaining  the highest SMS delivery rate possible.

Nexmo-BlockPerson3) Incorrect Sender ID: The Sender ID of a message is the “from” field that is shown on the users mobile phone when they receive the message. The fragmentation and complexity of the global bulk SMS industry is also shown here due to different countries and carriers having different rules as to what can be displayed. In the US, only numerical Sender IDs are allowed and all application-to-person messages must be sent from a text short code, whereas in the UK it can be alphabetical.

Nexmo-MessageLength4) Message Length: You may know that, typically, an SMS is 160 characters in length (if you were thinking 140, that’s Twitter). If you’ve read examples  through three however, you’ll know that nothing is as simple as it seems. Countries like Brazil only support messages of up to 157 characters of length. If your message length is over this limit, it will be rejected if your SMS provider doesn’t automatically split it into multiple messages. One of the main things to look out for is a link being split into two, rendering it unclickable.

Nexmo-Coding5) Encoding: Last but not least is the SMS encoding. 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. It’s important to know that different carriers and countries require different encoding. Some carriers simply will not deliver messages that are sent in unicode while others will deliver the message incorrectly.

We recommend that 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 that you aren’t missing any important information.

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