Given that the characters in your SMS are part of the GSM 7-bit encoding character set which contains all the of the most used ones (see table below) you can include up to 160 characters in a single SMS message.

Note that the following characters | , ^ , € , { , } , [ , ] , ~ , \ can also be used. However, each of these will be counted as two characters in the SMS message, not one. This might in turn have an impact on the length of your SMS and thus the cost.

Using any other character than stated above will make the SMS encode as Unicode, and each character will use more bytes leaving you with just 70 characters in one SMS.

When specifying the message body, the characters used as well as the length of the message will affect how many actual SMS messages are sent out. If you are using parameterization the length of each message may also vary depending on the recipient-specific data—find more on this topic here and here.

Most often you will probably only send one SMS to each customer, and this will be done as long as you don't load the SMS with more than 160 characters. Any SMS containing more than that will be split and sent as multiple distinct SMS messages (the customer will get them delivered and displayed as a single long message). A split SMS will be counted as >1 and billed accordingly.

You can use the table below to determine the actual number of SMS your message will create based on how many characters it will be provided with.

It's a good idea to put some thought into what sender name you want to display to your customer to ensure they know it's you. Bear in mind to keep within the limits of 3-11 characters (this is standard for most SMS suppliers).