Concatenated SMS sending

According to the SMPP protocol specification, the maximum length of one SMS to be sent is:

• for messages in Latin: 160 characters;

• for messages in Cyrillic: 70 characters.

SMS exceeding the maximum length are called multipart or concatenated SMS and are usually split into parts when sent. The length of one part is:

• for messages in Latin: 153 characters;

• for messages in Cyrillic: 67 characters.

To send concatenated SMS, one of the following three technologies is employed:

• UDH (user data header) is a special header at the beginning of the text of the SMS;

• SAR is analogue of the UDH header; due to the location in TLV fields, it will not reduce the size of one part of an SMS

• message_payload is TLV field hosting the entire message content

Detailed information about the above technologies can be found in the SMPP protocol specification.

⚠️IMPORTANT:

In each part of a multipart SMS, the values of the following fields must match:

• service_type;

• source_addr_ton;

• source_addr_npi;

• source_addr;

• dest_addr_ton;

• dest_addr_npi;

• destination_addr;

• esm_class;

• protocol_id;

• priority_flag;

• validity_period;

• registered_delivery;

• data_coding.

A message cannot be delivered until all of its parts have been received.

The wait time for all parts of a concatenated message is 10 minutes. If all parts are not received after this period, the message will not be sent.