The meaning of the `length`, `remaining` and `per_message` values returned by `SMSCounter.count()` depend on the encoding.
For GSM_7BIT_EX encoding, `length`, `remaining` and `per_message` count the number of 7-bit characters in the message, __including__ the escape character that must precede any characters in the "extended" character set. For example, the `length` of the message '€' is 2, because it takes 2 7bit characters to encode '€' in GSM_7BIT_EX.
For UTF16 and GSM_7BIT encoding, `length`, `remaining` and `per_message` count the number of characters (since all characters have an equal bit width).