A single SMS message can contain up to 140 bytes of information. When a message contains more than the maximum number of characters, the message is split into multiple parts. Depending on the recipient's mobile carrier and device, multiple messages might be displayed as a single message, or as a sequence of separate messages.
If your message uses only characters in the GSM 03.38 character set, also known as the GSM 7-bit alphabet, it can contain up to 160 characters. If your message contains any characters that are outside the GSM 03.38 character set, it can have up to 70 characters. When you send an SMS message, AWS End User Messaging SMS automatically determines the most efficient encoding to use.
You are billed for each message part that is sent. Phone numbers have a limit on the number of message parts they can send each second. If your message is split into two message parts, you are billed for each message part. Use the message part preview before you send your SMS message to see how many message parts it is. For more information about supported character sets, see SMS character limits. For more information about message size and throughput, see What are the Message Parts per Second (MPS) limits.
Using the message part preview
Open the AWS End User Messaging SMS console at https://console.aws.amazon.com/sms-voice/
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In the navigation pane, under Shortcuts, choose Message part preview.
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In the SMS message section, enter your SMS message. As you enter the message, the Part preview displays the encoding, number of characters, and SMS message parts.
