The SMS format limits the length of a message to 160 characters. If your message is longer than 160 characters, it will be sent as a multipart message (multiple messages to be combined into one at the receiving end). While most mobile service providers combine multipart SMS messages into one, some providers do not. In this case, the multipart message will be received as separate messages.
When entering your SMS message, check the Messages indicator below the SMS TEXT box to see how many SMS messages will be necessary to send the message. Check the Characters remaining indicator to see how many more characters you can enter in total. A multipart message can be up to 980 characters long. Be aware that the indicators will be inaccurate if you include SMS variables in the message, since the results of the variables will be different from the variable names. For example, if your business name is Testing123, the variable [BusinessName], which is 14 characters long, will be replaced with Testing123, which is 10 characters long.
For information about creating and sending SMS messages, see the following articles: