How are SMS lengths calculated? Follow

A standard SMS has a maximum of 160 characters. Messages that exceed 160 characters will result in a 'second' message, though the patient will still see this as one long message on their phone.

When a message is longer than 160 characters, this is referred to as a 'multi-part' message since it contains multiple standard-length messages (or 'parts'). Since each standard-length message (or 'part') contains 7 characters for invisible headers and footers (these denote which 'part' of the message is being sent, e.g. part 1 of 2), the total character limit per subsequent SMS becomes 153 characters per 'part'.

Below is a guide of how many messages are constituted by each character range up to 765 characters.

1 - 160 characters = 1 message (160 characters)
161 - 313 characters = 2 messages (160 characters + 153 characters)
314 - 466 characters = 3 messages (160 + 153 + 153)
467 - 619 characters = 4 messages (160 + 153 + 153 + 153)


Please Note: These ranges are calculated using standard English characters. If Unicode or Non-GSM characters are used, the ranges are slightly different. Additionally, Healthengine’s current SMS provider service caps messages at 466 characters, so this is the maximum allowable length in the Communicate product.

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