Help Center Unicode SMS The 70-Character Limit of Unicode Messages: A Deep Dive

The 70-Character Limit of Unicode Messages: A Deep Dive

Unicode Standard at Connection Software:

At Connection Software, our comprehensive support for sending SMS text messages embraces the Unicode character set, which is restricted to 70 characters per SMS. Our state-of-the-art APIs are adept at handling longer messages. When such messages are dispatched, they are sent to the recipient's device as a series of concatenated SMS messages. For a detailed understanding of Unicode, one can refer to resources provided by The Unicode Consortium and their frequently asked questions.

Rationale Behind the 70-Character Limitation for Unicode Messages:

An SMS in the GSM (Global System for Mobile Communications) format can accommodate a message body of up to 140 octets (8-bit bytes). The default alphabet for GSM is based on a 7-bit structure. This means that one can fit up to 

7/140×8  = 160 characters in a singular SMS.

However, Unicode messages employ the UCS-2 encoding, which allocates 2 octets for every character. Consequently, this restricts the character count to 

2/140​  = 70 characters for each SMS.