SMS segments and message length
Message Encoding
SMS messages can be encoded using different character sets, notably GSM-7 and Unicode. The choice of encoding impacts the maximum length of a message and the number of segments required for transmission.
Types of Encoding
GSM-7 (7bit)
GSM-7 encoding, the standard for SMS messages, accommodates most characters within its 128 Latin characters, numbers, and select special characters repertoire. Each character occupies one slot within the message, allowing for a maximum message length of 160 characters.
GSM-7 Encoding Characters
@ | ฮ | SP* | 0 | ยก | P | ยฟ | p |
ยฃ | _ | ! | 1 | A | Q | a | q |
$ | ฮฆ | " | 2 | B | R | b | r |
ยฅ | ฮ | # | 3 | C | S | c | s |
รจ | ฮ | ยค | 4 | D | T | d | t |
รฉ | ฮฉ | % | 5 | E | U | e | u |
รน | ฮ | & | 6 | F | V | f | v |
รฌ | ฮจ | ' | 7 | G | W | g | w |
รฒ | ฮฃ | ( | 8 | H | X | h | x |
ร | ฮ | ) | 9 | I | Y | i | y |
LF* | ฮ | * | : | J | Z | j | z |
ร | ESC* | + | ; | K | ร | k | รค |
รธ | ร | , | < | L | ร | l | รถ |
CR* | รฆ | - | = | M | ร | m | รฑ |
ร | ร | . | > | N | ร | n | รผ |
รฅ | ร | / | ? | O | ยง | o | ร |
LF is a Line Feed control
CR is a Carriage Return control, or filler
ESC is an Escape to extension table
SP is a Space character
The following characters are included in the GSM-7 character set, but they represent two characters when used in a text message:
Unicode
Unicode encoding supports a broader spectrum of characters, including non-Latin languages, emojis, and special symbols. However, each Unicode character occupies two slots, effectively halving the maximum message length to 70 characters.
SMS segments
When an SMS message exceeds the character limit, it undergoes segmentation, dividing it into multiple segments for delivery. Each segment, although sent separately, is seamlessly reassembled on the recipient's device to form the original message.
Each segment is charged separately.
Maximum number of segments
SMS segmentation is not without limitations. Exceedingly long messages may not be delivered, as carrier networks have constraints on the maximum message length. For GSM-7 messages, the maximum length is 1377 characters, while for Unicode messages, it's 603 characters.
Best Practices
To optimize your SMS campaigns:
Keep messages concise and within recommended character limits to ensure successful delivery.
Use GSM-7 encoding for messages containing only Latin characters and numbers, and Unicode for messages with non-Latin characters, emojis, or special symbols.
Avoid excessive use of special characters or formatting to minimize the number of segments required for transmission.
Understanding the dynamics of SMS message length and segmentation empowers you to craft impactful messages that resonate with your audience. By adhering to best practices and leveraging the insights provided, you can enhance delivery rates, improve recipient experience, and boost engagement in your SMS campaigns. Should you have any inquiries or require further assistance, our Support team is readily available to assist you.
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