Text message (SMS): what it is, how it works and examples
The simplest channel to reach your customers' phones
A text message is a short written message sent from one phone to another over the mobile network. It is also known as SMS (Short Message Service). It reaches any mobile phone, even one with no internet connection or apps installed.
An SMS can hold up to 160 characters. If the text is longer, it is split into several parts that the phone joins back together. That is why anyone writing a text message learns to say what matters in just a few words.
How does a text message work?
When you send an SMS, your phone passes it to your carrier’s message center. That center stores it and delivers it to the destination phone as soon as it is available. If the phone is switched off, it tries again later.
Everything happens over the telephone network, not the internet. That is its big advantage: it works with basic coverage, on any phone brand and without downloading anything.
The first SMS was sent on December 3, 1992 in the United Kingdom. It said “Merry Christmas” and was sent from a computer to a mobile phone. More than 30 years later, SMS is still the channel banks, stores and services use for important notifications.
Send SMS to your customers from Mailrelay
Write the message, see how many characters you have left and send it from the same dashboard as your emails.
How many characters does a text message have?
It depends on the characters you use:
- 160 characters if you only use letters without accents, numbers and basic symbols (GSM-7 alphabet).
- 70 characters if there is at least one emoji or a character outside that alphabet, such as á, í, ó or ú.
If you go over, the SMS is split and each part loses a few characters so the parts can be joined later: 153 per part in GSM-7 and 67 in Unicode. Each part counts as one SMS on your bill. You can find all the details and the list of characters in the entry on the SMS character limit.
Text message, WhatsApp and RCS: what are the differences?
Today SMS coexists with messaging apps and with RCS messaging, its evolution. These are the main differences:
| Text message (SMS) | RCS | ||
|---|---|---|---|
| How it arrives | The carrier’s mobile network | Internet (data or wifi) | Internet, from the phone’s messaging app |
| What the recipient needs | Just a mobile phone number | The app installed | A compatible phone and app |
| Length | 160 characters per SMS | No practical limit | No practical limit |
| Content | Text only | Text, photos, videos and buttons | Text, photos, buttons and read receipts |
| Business use | Notifications, codes and promotions | Customer service and sales | Rich branded messages |
SMS wins on reach: it gets to everyone. WhatsApp and RCS win on format, but they depend on the recipient’s app and connection.
What are text messages used for in marketing?
Businesses use SMS marketing for short, urgent messages that are best read right away. It works better as a complement to email than as a replacement. Here are 5 examples you can adapt:
| Use | Example message |
|---|---|
| Promotion with a deadline | “STORE: Today only, 20% off the whole site with TODAY20. Until 11:59 pm. Reply STOP to unsubscribe” |
| Appointment reminder | “DENTAL SOL: We look forward to seeing you tomorrow at 10:30. If you can’t make it, reply NO to this SMS” |
| Order notification | “STORE: Your order 1234 arrives today between 4 and 8 pm. You can track it at this link: (link)” |
| Verification code | “Your access code is 482913. Don’t share it with anyone” |
| Payment reminder | “GYM: Your October fee is still pending. You can pay it at this link: (link)” |
The examples are written without accented words (á, í, ó, ú) or emojis, so they fit in a single 160-character SMS. Verification codes are known as OTP, and order or payment notifications are part of transactional SMS. If you want more collection templates, see these examples of payment reminders by email, SMS and WhatsApp.
Advantages and limits of text messages
Advantages:
- They reach everyone. All you need is a mobile number, with no apps or data.
- They are read quickly. Most people look at an SMS a few minutes after receiving it.
- They are simple. A short, clear message is easy to write and easy to understand.
Limits:
- Little space. 160 characters force you to get to the point.
- Cost per send. Each SMS (or each part) is paid for, unlike email.
- Consent. To send commercial SMS you need each person’s prior permission and an easy way to unsubscribe. In Spain, the LSSI requires it.
How Mailrelay helps you
With Mailrelay you can send mass SMS from the same dashboard as your newsletters. You import the numbers, write the message and the editor counts the characters in real time, so you know how many SMS you will pay for. Afterwards you see the delivery statistics.
You can also add SMS to your automations, for example to send a birthday greeting or remind someone about an abandoned cart. To use your brand name as the SMS sender in Spain, you register it in the CNMC alias registry from the dashboard itself, under SMS > SMS alias registry.
If you only want to send a few messages, see how to send SMS from your computer for free or in bulk. Prices per package are on the SMS pricing page.
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Frequently asked questions
Is a text message the same as an SMS?
Yes. SMS is the technical name for the text message sent over the mobile network. WhatsApp or Telegram messages are also text, but they travel over the internet and are not SMS.
How many characters does a text message have?
Up to 160 if you only use basic characters and 70 if you include emojis or accented vowels such as á. If you go over, it is split into several SMS.
Do I need internet to receive a text message?
No. SMS arrives over the carrier’s network; all you need is coverage. That is why it is used for notifications and security codes.
What is an MMS?
It is the multimedia version of SMS: it lets you send photos, audio or video over the mobile network. We explain it in the entry on MMS.
Can I send text messages to many customers at once?
Yes, with an SMS sending platform. You just need their consent, and you must offer a way to unsubscribe in every send.