Writing transactional SMS: the key fact first, references and amounts, and one part only

The short answer: a good transactional SMS says what happened in the first sentence, carries the reference (order, invoice or booking number), gives the next step and fits in a single part: up to 160 characters in plain letters, or only 70 if the text has a letter outside the basic alphabet, such as the Portuguese «ã» or «ç». Cut everything that belongs in a formal letter.

The order that works

1	What happened. «Order shipped», «Payment received», «Appointment booked». It is what the customer reads in the notification, before opening the message.

2	The reference. The order, invoice or service number, exactly as the customer sees it on the receipt or on your website.

3	The fact that matters. The amount, the date, the time, the collection code.

4	The next step or the contact. Where to collect, by when, or how to reach you, because the SMS cannot take replies.

Before and after

Version	Message	Parts
Before	Dear customer, we are pleased to let you know that your order number 8812, placed on our website on 10 November, has now been dispatched and will reach you soon.	2 (161 characters: one over the single-part limit)
After	Order no. 8812 shipped today. Arrives by 15/11. Questions? Check its status on our website.	1 (91 characters)

The second one says more (the arrival date and where to track the order) and costs half. In a system sending thousands of notices a month, that difference shows in the balance.

The characters that cost more

What you type	What happens
Plain letters, digits, common punctuation, plus é, à and a capital Ç	Basic alphabet: up to 160 characters in one part; above that, up to 153 per part.
A single ã, õ, á, í, ó, ú, â, ê, ô, lower-case ç, an emoji or curly quotes	The whole message switches to Unicode: up to 70 in one part; above that, up to 67 per part.
€ [ ] { } ^ ~ \ \|	Count as 2 characters in the basic alphabet.

Watch out for text pasted from a document: it brings curly quotes and long dashes that switch the message to Unicode without anyone noticing. Names do the same: «João» in a personalised text is enough. The technical background is in GSM-7 or Unicode.

Dates, amounts and abbreviations

1	Dates in figures (15/11) and clear times (17:30): short and unambiguous.

2	Amounts with the currency, as on the receipt: 1,500 USD.

3	Only abbreviations everyone knows (no., Dr). Text-speak saves little and looks careless.

4	No shouting in capitals, except for one word such as ALERT in a security notice.

Before a text goes into your system, try it. In the API Sandbox the answer shows how many parts and which alphabet it would use (parts and encoding) without sending anything; in the SMS Center, the page shows the parts and credits before you confirm.

Ready to have these texts go out from your system on their own? See Transactional SMS.

See Transactional SMS

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