How SMS Works for Text Message Marketing

Learn how SMS works for text messages and how it moves through cell towers, aggregators, and wireless networks to reach your recipients.

When you send a letter in the mail, it flows through an intricate network of post offices, sorting facilities, and distribution centers. 

Then, almost like magic, it appears in your recipient’s mailbox a few days later.

SMS messages follow a similar process, but digitized. Instead of transporting directly to your recipient’s phone, the text bounces between a series of checkpoints instantly. 

Not only do those checkpoints move your text’s data from one device to the other, but they also help protect people from spam and fraudulent messages.

Let’s dive into how SMS messaging technology works for texting friends, family, and customers.

What is SMS Messaging?

SMS, which stands for Short Message Service, is a way to send concise text messages between mobile phones.

When SMS was first introduced in 1992, mobile networks had limited capacity to transmit data, so the messages needed to be short (160 characters or fewer) to conserve network resources. Thanks to advancements in texting technology, we can now use extended SMS messages to send more than 160 characters into one text.

If you want to send even longer text messages to your customers, you can use MMS messaging, which allows up to 1,600 characters and media (like images, videos, audio, GIFs, and PDFs).

How Does SMS Work?

There are two ways to send SMS messages: peer-to-peer (P2P) messaging and application-to-person (A2P) messaging. Both deliver text messages to mobile devices, but they take different routes to get there.

The Journey of a P2P Message

Let’s say you want to text a friend that you’re running late for dinner. You type up the message, “Hello! Sorry, I’m running late. Be there in 10.” 

Here’s how your message reaches your friend:

Step 1: Convert the Text into the GSM 7-bit Alphabet

First, your phone converts your message into the GSM 7-bit alphabet, which breaks your text up into the tiniest bits of data that can be transmitted to a cell tower.

This includes your message and some basic information about it, like its timestamp and the recipient’s phone number.

Step 2: Send the Text to a Short Message Service Center via a Cell Tower 

Your phone sends the tiny message to a nearby cell tower. Once the cell tower receives your message, it sends it to a system called the Short Message Service Center (SMSC). 

Step 3: The SMSC Sends the Text to a Cell Tower Near Your Friend

The SMSC checks who your friend — the recipient — is and then checks if they are in range. If they are, the message is then sent to the tower nearest to them and then, finally, their mobile phone.

Step 4: Your Friend’s Phone Converts the Text to Your Original Message

Your friend’s phone then turns the messages back from the GSM 7-bit alphabet into standard English characters by using the same code, but in reverse.

If the SMSC can’t find the phone, the message will just bounce around in its system until the moment the phone reconnects, at which point it sends it immediately.

The Journey of an A2P Message

If you’re sending SMS messages from an SMS marketing platform (like SimpleTexting), your text takes a different path to get to your customers’ phones.

Whether you’re sending a mass text message or a two-way message, the sending process is the same: 

Step 1: Compose the Text in Your A2P Messaging Provider

Use an A2P messaging provider to compose the text message you want to send. You can send the message right away or schedule it for later. Your A2P provider also monitors messages for prohibited content.

Step 2: The A2P Messaging Provider Sends the Text to an Aggregator

Next, your A2P messaging provider sends the message to an aggregator (also known as an SMS gateway). The aggregator acts as a middleman between the A2P provider and the wireless carriers and helps prevent spam messages from reaching the carriers’ networks.

Step 3: The Aggregator Sends the Text to Your Contacts’ Wireless Carriers

The aggregator receives the text message from the A2P provider and forwards it to the wireless carriers that are associated with the recipients’ mobile phone numbers.

Step 4: The Wireless Carriers Send the Text to Your Contacts

After receiving the text message from the aggregator, the wireless carriers responsible for the recipients’ phone numbers deliver the message to their respective devices. The message then appears as a regular SMS on the recipients’ phones, allowing them to read and respond to it.


What is the difference between a text message and an SMS message?

The difference between a text message and an SMS message is that a text is a kind of message that’s sent electronically, while an SMS message specifically refers to short messages send over wireless networks. SMS is a standard protocol used for sending short text messages between mobile devices.
To use SMS texting, you simply need a mobile phone with texting capabilities or a computer texting app. Open the messaging app, select the recipient’s phone number, type your message, and hit send. The message will be delivered to the recipient’s phone, and they can read and respond to it.
No, SMS doesn’t require an internet connection. Unlike WhatsApp or Facebook Messenger, SMS uses the cellular network to transmit messages. As long as you have cell service and a text messaging plan, you can send and receive SMS messages without Wi-Fi.
Text messages travel through the air using radio waves. When you send a text message, your phone converts the message into a series of binary digits and transmits it as radio signals.
These signals are then picked up by cell towers or base stations, which relay the message to the recipient’s cellular network. The recipient’s phone receives the radio signals, converts them back into text, and displays the message.
The technology used in SMS is based on the Global System for Mobile Communications (GSM) standard. SMS messages are transmitted using the signaling channels of the GSM network, allowing for the exchange of short text messages between mobile devices. The GSM standard provides a reliable and efficient way to send and receive SMS messages across different cellular networks.
The difference between MMS and SMS is that MMS uses a different communications system that allows people to send multimedia content like images, audio, and video. MMS messages support up to 1,600 characters, while SMS supports around 160 characters.
Over-the-top (OTT) messaging apps are instant messaging services provided by third parties. OTT messages are often seen as an alternative to SMS and include apps like WeChat, Facebook Messenger, and WhatsApp. They bypass the telecommunications companies and mobile networks by using the internet to transfer data.

This article was originally written on January 19, 2021, by Drew Wilkinson. It was refreshed and repurposed on July 12, 2023, by Dani Henion.