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What is the maximum message length?

A single plain text message may be up to 160 characters long, or a long concatenated message may span several single messages.

Number of SMS Maximum message length
1 160
2 306
3 459

In theory it is possible to utilise 255 messages (39,015 characters) for a concatenated SMS. However, 3 SMS (or 459 characters), is generally considered to be the longest length message that will be displayed on the majority of mobile handsets. SMS is therefore limited to 459 characters to ensure maximum compatibility.

The table below shows the maximum hex encoded lengths per number of SMS for binary and UCS2 messages.

Number of SMS Binary Data Including UDH Maximum Length Hex UCS2 Maximum Length Hex
1 266 280
2 512 536
3 768 804

Both a User Data Header (UDH) and a concatenation header are required for multipart binary data. The table above takes this into account and uses the hex encoded lengths as this data should be submitted to the HTTP SMS system in hex encoded format.