National Language Shift

In addition to the standard SMPP 3.4 features, we support National Language Shift (NLI), which enables the use of language-specific characters. This functionality is available over SMPP (opens in a new tab), Broadcast, and HTTP API (opens in a new tab).

National Language Shift uses language-specific character sets that allow you to send special characters at the same cost as standard GSM-7 messages. The tables below list supported languages.

For example, Turkish characters such as ğ, Ğ, € can be sent at the cost of a single GSM-7 character. Normally, these would require Unicode, reducing the message length to 70 characters, but with NLI and User Data Header (UDH), the limit is 155 characters.

Locking Shift vs. Single Shift

• Locking Shift: Characters from the extended set do not reduce the message length (remains 155 characters).
• Single Shift: Each extended character requires an escape character, which reduces the available message length by 1.
  • Example: In Spanish, the letter Ú is only available in the single shift set. If 3 such characters are used, the length reduces from 155 to 152 characters.
  • Example encoding: 1B55 → 1B is the escape character, 55 is Ú from the extended set.

Technical notes

• Language selection is defined in the UDH using the Information-Element-Identifier (IEI) to specify single or locking shift.
• The ESM class parameter must be set to 64.
• Valid data coding values are 0 or 1.

Locking Shift example UDH

Single Shift example UDH

UDH Identifier reference

Below is a UDH reference for each language and here is a detailed character set reference for GSM 7 (opens in a new tab).