The Bulk 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.
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.
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 are also shown here due to different countries and carriers having different rules as to what can be displayed.
You may know that, typically, an SMS is 160 characters in length. 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.
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.