In order to send a flash SMS on smpp protocol we use the data-coding field (ver. 3.4 or 5.0) inside the PDU. On the other hand, if we want to send a normal sms in any language we use the same field so as to support the extended characters in that language. So smpp protocol has added some optional fields, which are called TLV so as to support such a functionality. In gsm protocol there is no such a problem because they introduced 'message class' see : 3GPP protocol . So, to come back to smpp protocol, they use the TLV dest_addr_subunit but is not clear how to use it so as to send a sms with ucs2. Can you give an example or a way to support that feature?
For Flash SMS, you set TLV DATA_CODING to 0x18 value.