Long Messages
A standard SMS message contains a maximum of 160 characters. Longer messages are possible, however please be aware that exceeding 160 characters will constitute, and be charged, as an additional message even though the recipient will see your message as a single message on their handset.
When a message is longer than 160 characters, this is referred to as a multi-part message as it contains multiple messages (or multiple-parts). The total SMS limit for each subsequent part then becomes 153 characters, as 7 characters are used as invisible start and end markers for each part.
1 – 160 characters = 1 Message
161 – 306 characters = 2 Messages
307 – 459 characters = 3 Messages
460 – 612 characters = 4 Messages
613 – 765 characters = 5 Messages
766 – 918 characters = 6 Messages
919 – 1071 characters = 7 Messages
1072 – 1224 characters = 8 Messages
Character Counter
This link helps you determine how many characters your SMS message will contain: http://smscharactercount.com
GSM Basic Character Set
A message is classified as a standard message when it contains characters from the GSM Basic Character Set.