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Top 5 reasons your SMS isn’t being delivered

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Developers 5 min read | wrote in blog on March 21, 2019

If you’re a global company, SMS communication across all your localities can be a challenging proposition.  Each country, along with its carriers, has its own rules about what type of traffic is allowed and understanding the complexities of ensuring message delivery can be daunting. If your messages are not meeting their intended destination, this could be for a number of reasons. In this blog post, we’ll help you narrow down the most likely culprit, as well as avoid potential issues for all your messaging.

  • Region restriction

When you sign up for a developer account, your account will be topped up with free credits and will be region restricted to the country associated with your mobile phone number. You’ll be able to use these credits in your country in most cases, but if you’re unable to it may be due to region restrictions. If you find yourself unable to use your credits, get in touch with us on our slack channel or email us at developers.

A postpaid account may also have region restrictions depending on how your account has been sent up. If you would like to add further allowed destination countries to your account, this can be arranged by your account manager or by contacting support.

  • Region regulation

MessageMedia sends messages globally which means we adhere to the regulatory environment in the destination country of each message. This creates unique restrictions in each location, but it also means that we have unique recommendations about how to optimise usage in your country. In some countries such as the United States, alpha tags are not supported, so we recommend shortcodes. In India, messages sent between 9 pm and 9 am will not be delivered but rather queued for delivery once this “curfew” ends. If you’re experiencing issues that are related to region restriction the support team will help you to identify what the restriction is an make a recommendation on how to address it.

  • Validity

There are a few cases in which the number you are trying to send to may be invalid. The first example of when this may happen is if the phone number has been retired or deactivated. This is usually due to customers changing carriers or cancelling contracts. In some cases, your customer filled out the form incorrectly when signing up, or deliberately put in a false number. Another cause of this is the absence of the international country code in the phone number. Because MessageMedia is responsible for delivering about 1.2 billion messages worldwide, all numbers need to be sent in an international format with the correct code prefixed to it.

MessageMedia provides a lookup feature that will help you to ensure the validity of your numbers and reduce wasted spend on messages that didn’t reach the person you wanted to reach. This feature enables you to find out mobile carrier information about any mobile number, in real-time, anywhere in the world. You can use this information to identify invalid numbers, separate mobiles and landlines, and identify carriers to determine which are low cost.

  • Carrier filters

In addition to regulatory restrictions, some carriers in specific localities have restrictions on what they will allow on their network. In Malaysia, alpha tags are all overwritten with a random Malaysian number or occasionally a shortcode. Filtering alpha tags is the easiest way for spam filters to block unwanted traffic and attribute all messages to a source address. By doing so, mobile operators can block undesired traffic without affecting permitted traffic. In other countries, a registered alpha tag will actually increase deliverability. If sending internationally and for best results, it is a good idea to try and get a local dedicated number or a registered alpha tag (depending on your country). You can reach out to your Account Manager to work out the best approach for your region.

  • Encoding

Encoding is the process of putting a sequence of characters into a special format for transmission. Typically, messages are sent using either Unicode, which allows for 70 characters, or the global standard GSM which allows 160 characters. Different encoding is required by different carriers and countries. In the United States, Unicode is the standard encoding method for SMS messages. GSM encoded messages may be unreadable when sent – and some carriers may refuse to deliver these messages entirely. Encoding also has other impacts outside of deliverability. Some carriers may not display all emojis correctly or may filter Unicode in unexpected ways. If unexpected things are happening to your messages, get in touch with MessageMedia support, who can pinpoint the issue and recommend a course of action.

As an 18-year-old veteran in the industry, MessageMedia has adapted to provide a high-availability, high-throughput and globally available messaging services. Our support team can assist you with optimising your message send, and troubleshooting issues. To find out more about our Messaging API and get started click here.


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