Can I send messages longer than the specified character limit?

Yes, you can. A message that contains only GSM characters and is longer than 160 characters will be split into parts of 153 characters each. A message that contains one or more unicode characters and is longer than 70 characters each will be split into parts of 67 characters each. This is to accommodate for UDH headers that ensure that the SMS is shown as a single concatenated message on the end users mobile handset