To use Unicode Messages when sending via SMPP, please ensure you set your DCS value to 8 to ensure Unicode is encrypted properly.
If you wish to send over 70 characters using Unicode you will need to split your SMS into parts of 67 characters and include the headers.
For more information on SMPP, please see our documentation on SMPP API.
For more information on Unicode, please see the following knowledgebase article on Understanding Unicode Characters and Messages.