Messaging • Last Updated 5/7/2024

What is SMS? How short message service works

Explore the advantages of SMS, how it works, and how it compares against other messaging services.


By Emily Bowen

Sending SMS text message

If you’ve ever wondered how SMS works and why it's so widely used, you're in the right place.

In this guide, we’ll demystify SMS and show why it's crucial in today's communication landscape. Whether you're curious about the technology behind those concise text messages or seeking to leverage SMS marketing for your business, this blog post is your ultimate resource.

What is SMS?

SMS stands for Short Message Service, a text messaging service built into most mobile phones and other mobile devices.

SMS uses standardized communication protocols to send text messages from one device to another. It's ideal for sending short, text-only messages. The fact that it’s cost-efficient, widely available, and standardized makes it the most ubiquitous text messaging service.

How does SMS work?

Here’s what happens when you send an SMS message:

  1. The message gets transmitted from the sending device to the nearest cell tower.
  2. That cell tower passes the message to an SMS center (SMSC).
  3. The SMSC forwards the message to a cell tower near the receiving device.
  4. That tower sends the message to the recipient’s device.

SMS and its alternatives

SMS is a simple yet powerful tool that enables communication between devices using standardized protocols. However, it’s not the only messaging service available. Let's compare it with its alternatives.


MMS (Multimedia Messaging Service) is similar to SMS in terms of device compatibility. However, MMS can send multimedia content—images, videos, and audio—in addition to transmitting text.

Check out our SMS vs. MMS guide for a more detailed comparison between SMS and MMS.


Rich Communication Services (RCS) is a protocol aimed at replacing SMS messages with a richer text message system. RCS can transmit in-call multimedia, provide phonebook polling, and transmit other types of content. It also allows for longer (up to 8,000 characters) messages. However, RCS's adoption has been slower due to device and network limitations, as well as a lack of universal standards.

For a more detailed comparison between SMS and RCS, check out our SMS vs. RCS guide.

SMS vs. OTT applications

OTT applications are another messaging solution. They offer additional functionality over SMS, such as the ability to send multimedia content. However, they require an internet connection to work and are often used as advertising platforms.

For more information on OTT applications and how they compare to SMS, refer to our OTT Messaging guide.

Advantages of SMS

As one of the most commonly used messaging services, SMS offers efficient mass communication and a personalized experience. Let’s take a look at some of the advantages that make SMS a popular choice for both personal and business communication.

Ubiquity and compatibility

SMS is nearly universal. It works on almost all mobile phones, regardless of the device's age or model. Its wide compatibility means you can reach almost anyone with a mobile phone, regardless of the type of device they’re using.

No internet required

Unlike many messaging apps, SMS doesn't require an internet connection. This feature makes it a reliable form of communication, even in areas with poor or no internet connectivity.

Immediate and direct communication

SMS messages are delivered almost instantly, making them ideal for time-sensitive communications. They are also delivered directly to the recipient's device, ensuring they see your message.

High open rates

SMS messages have a high open rate compared to other forms of communication, such as emails. Most people open text messages within a few minutes of receiving them, making SMS an effective way to ensure your message is seen.


Sending SMS messages is generally inexpensive, making it a cost-effective communication solution, especially for businesses that need to send messages to many people at once.

Disadvantages of SMS

While SMS has numerous advantages, it also has certain limitations and disadvantages when compared to other messaging services. Let's explore some of the drawbacks associated with SMS:

Character limit

SMS has a character limit of 160 characters per message. This restriction can be limiting when trying to convey complex or lengthy information. In contrast, other messaging services, such as MMS or even email, allow for longer, more detailed messages.

Lack of rich media

SMS is primarily a text-based medium and doesn’t support the transmission of rich media such as images, videos, or documents. This limitation can hinder the ability to share multimedia content or interactive elements that may be more engaging or informative in certain contexts.

Limited formatting options

SMS messages lack advanced formatting options like font styles, colors, or layouts. This constraint restricts the visual presentation and branding opportunities available in other messaging platforms, where you can customize content to align with a specific brand or aesthetic.

No read receipts or typing indicators

Unlike some messaging services, SMS doesn’t provide read receipts or typing indicators, which inform the sender when a message has been read or when the recipient is in the process of composing a response. This lack of real-time visibility can sometimes lead to uncertainty regarding message delivery and recipient engagement.

No offline access

SMS messages require a cellular network connection for both sending and receiving. Unlike some messaging services that allow users to access and send messages even when offline, SMS depends on network coverage, limiting its functionality in areas with poor or no cellular connectivity.

Despite these limitations, SMS remains a reliable and widely adopted means of communication due to its broad compatibility, immediate delivery, and high open rates. It excels in situations where simplicity, speed, and accessibility are crucial. By understanding its limitations, you can make informed decisions about when SMS is the most suitable messaging option and when other platforms may better meet your communication needs.

What is SMS integration?

SMS integration helps you incorporate SMS functionality into existing systems, applications, or platforms, connecting SMS capabilities with other software or services to enable seamless communication via text messages.

With SMS integration, you can leverage the power of SMS within your existing workflows, customer engagement strategies, or internal communication systems. By integrating SMS functionality, you can automate and streamline various processes, enhance customer interactions, and improve overall communication efficiency.

You can achieve SMS integration through various methods, depending on the specific requirements and the systems involved. One of the most common approaches is through an SMS API, which provides instructions and protocols for programmatically sending and receiving SMS messages. With SMS integration, you can automate your communication processes, making them more efficient and effective.

For a more detailed guide on SMS integration, check out our SMS API Explained guide.

Experience the reliability of SMS with Telnyx

Whether you're a business looking to reach your customers or an individual wanting to stay connected with friends and family, SMS offers a reliable and efficient way to send messages.

Choosing SMS for your communication needs is a decision that brings many benefits. It can streamline your messaging process, boost customer satisfaction, and significantly improve your outreach when effectively utilized. Ignoring the potential of SMS just because a flashy new option like RCS has come along could result in overlooked opportunities and ineffective communication.

To fully experience the positive impact of SMS on your business, it's critical to have a reliable communication partner like Telnyx. With Telnyx's advanced SMS API, you can send personalized, timely, actionable messages that resonate with your customers. Our automation features ensure consistent message delivery, and our segmentation capabilities enable you to tailor your messages based on your customers' preferences.

Our global network, comprehensive API support, and dedicated team of SMS experts make the transition smooth, allowing you to port your existing numbers and start sending SMS messages seamlessly. Additionally, Telnyx offers competitive pricing, ensuring that the cost of sending SMS doesn't exceed the value it brings to your business.

Let Telnyx empower your business to send impactful messages that provide effective communication and foster strong customer relationships. Begin your journey towards better business communication and customer satisfaction today.

Talk to a Telnyx SMS expert to find out how your business can leverage the power of SMS with Telnyx.

Looking for more information on SMS? Check out some of these other resources:

  • Take advantage of deliverability insights from 1 billion+ messages with our 2023 Guide to SMS and MMS.
  • Visit our Developers Center for a robust catalog of SDKs in several coding languages like Python, Ruby, PHP, Node, and .NET to help you programmatically build a powerful SMS communications platform with ease.
  • See how Telnyx compares to a top SMS competitor.
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