Concatenated SMS Messages

Profile Headshot of Nisha Bhakar
Nisha Bhakar

mins read

May 8, 2024

Why Use Concatenated SMS Messages

Key Takeaways

  1. Concatenated SMS messages lets you send messages which are more than the character limit i.e. 160. This can be used to send marketing messages or any other important announcements
  2. Concatenated SMS messages are divided into segments of 153 characters each. These segments are then visible on recipient's end as one continuous text
  3. The overall length of the concatenated SMS messages depends on the number of segments allowed by the mobile network and the character encoding used
  4. Concatenated SMS messages are used for seamless communication, enhanced user experience and cost efficiency
  5. To enable concatenated SMS messages for your business, you can use an SMS API provider like Message Central

Concatenated SMS messages, also known as long SMS messages, allow you to send texts that exceed the standard 160-character limit. This feature is particularly useful when you need to convey longer cascading messages, such as detailed information, marketing campaigns, or important announcements, without splitting them into multiple separate texts.

How do Concatenated SMS Messages Work?

When you send a concatenated SMS messages or text blasts, it is divided into multiple parts, called message segments or message parts. Each message segment has a maximum length of 153 characters. The mobile network then combines these segments on the recipient's device, ensuring that the message is displayed as one continuous text.

To indicate that a message is a part of a concatenated SMS, a 7-byte header, known as the User Data Header (UDH), is added to each segment. This header contains information about the message, such as the total number of segments and the order in which they should be arranged.

For example, imagine you want to send a 300-character message for an SMS campaign. This message will be divided into two segments: the first segment will contain 153 characters, and the second segment will contain the remaining 147 characters. When the recipient receives these segments, their device will combine them to display the complete message.

Maximum Length of Concatenated SMS Messages

The maximum length of a concatenated SMS message depends on the number of message segments supported by the mobile network and the character encoding used.

For messages using the GSM character encoding (Latin-based languages), each segment can hold up to 153 characters. This means a two-segment message can contain up to 306 characters, and a three-segment message can contain up to 459 characters.

For messages using Unicode encoding (non-Latin languages), each segment can hold up to 134 characters. Therefore, a two-segment Unicode message can contain up to 268 characters, and a three-segment Unicode message can contain up to 402 characters.

It's important to note that the actual maximum length may vary depending on the SMS provider and the recipient's mobile network.

Why Use Concatenated SMS Messages?

Infographic Explaining Why Use Concatenated SMS Messages by Message Central.
  1. Seamless Communication: Concatenated SMS allows you to send longer messages without any interruptions or breaks, ensuring that your recipients receive the complete information.
  2. Enhanced User Experience: By sending concatenated SMS, you provide a better user experience by avoiding the need for recipients to piece together separate messages.
  3. Cost-Effective: Sending concatenated SMS with a single long message can be more cost-effective than sending multiple separate SMS messages and driving the aggregate SMS pricing down.
  4. Efficient Marketing: Concatenated SMS allows marketers to convey detailed messages, such as promotional offers or product descriptions, in a single text, increasing the effectiveness of their campaigns.

How to Send Concatenated SMS Messages?

To send concatenated SMS messages, you can use an SMS provider or an SMS API that supports this feature. Most SMS providers automatically handle the segmentation and reassembly of messages for you, ensuring that your recipients receive the concatenated message seamlessly.

Ensure that your SMS provider supports concatenated SMS and provides guidelines on how to format and send these messages. Each provider may have specific requirements, such as the character encoding to use and any limitations on the number of segments allowed. You can also get in touch with the team at Message Central to enable campaigns powered by concatenated messages.

Considerations for Concatenated SMS Messages

While concatenated SMS messages offer many advantages, there are a few considerations to keep in mind:

  1. Segment Limitations: Different mobile networks may have restrictions on the maximum number of segments they support for concatenated SMS messages. It's important to check with your SMS provider and understand the limitations imposed by the recipient's mobile network.
  2. Character Encoding: If you plan to send non-Latin languages or special characters, such as emojis, in your concatenated SMS messages, ensure that your SMS provider like Message Central supports Unicode encoding. This will affect the overall character limit per segment and the total length of the concatenated message.
  3. Message Cost: Keep in mind that each message segment is typically billed as a separate SMS. Sending longer concatenated messages may incur higher costs compared to shorter, single-segment messages.  
  4. Delivery Confirmation: Delivery reports for concatenated SMS messages may differ from those of single-segment messages. Instead of receiving separate delivery reports for each segment in an SMS dashboard, you will typically receive a single delivery report indicating the success or failure of the entire concatenated message.


Concatenated SMS messages provide a convenient and effective way to send longer text messages without splitting them into multiple individual texts. By understanding the maximum length, the encoding limitations, and the considerations involved, you can leverage concatenated SMS to deliver detailed information, improve user experience, and enhance your communication strategies.

Ready to Get Started?

Build an effective communication funnel with Message Central.

Weekly Newsletter Right into Your Inbox

Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.