Get started
Working with SMS

Shrawani Bhattarai
Shrawani Bhattarai
  • Updated

SMS, or Short Messaging Service, is a powerful communication tool that allows businesses to engage directly with customers through concise, timely messages. Pendula enhances this by enabling conversational SMS, where recipients can respond to messages and trigger automated follow-up actions. Pendula integrates seamlessly with your data sources, enabling automated actions based on specific events or conditions such as payment confirmations, invoice deliveries, or the start of a customer relationship. This integration allows for dynamic and contextually relevant communications that keep your audience engaged and informed.

Best practices for SMS communications

Understand the legal obligations of using SMS

When using SMS for marketing and communication, it is crucial to comply with legal standards applicable to the countries you operating within. Best practices to ensure consumer protection and privacy:

  • Always obtain either express consent before sending marketing SMS. Without this, messages could be considered spam.
  • Clearly identify your organisation within the SMS to avoid any ambiguity about the sender.

The mobile phone number your SMS are sent from is unique to your business and will not change. You might like to suggest to your customers that they save this number or add it to their contact list for future communication.

  • Provide recipients with an easy and clear way to opt out of receiving further communications. This can be achieved by including a simple opt-out instruction in every message, such as "Reply STOP to unsubscribe."
  • Ensure you are capturing and referring to your customers' communication preferences when sending out SMS, and always have a clear path for them to opt out if they wish.
  Hi [Name], this is [Your Company Name]. Thank you for signing up for the event!
  Visit [Link] for details. To opt-out of future messages, reply STOP.

Start with accurate data management

Pendula is directly connected to your data source. Keep your data source clean and up to date to make the most of any SMS communication. This includes:

  • Consistently updating and verifying mobile phone numbers and communication preferences across your contact records. This ensures that your messages reach the intended recipients without errors.
  • Checking your database to eliminate duplicate records. Sending multiple messages to the same phone number can lead to increased costs and customer dissatisfaction.
  • Store mobile phone numbers in international format (e.g., +61 for Australia), without any extra characters like spaces or text. This standardisation is crucial for global message delivery and ensures that inbound messages are correctly associated with customer records.

Why do mobile phone numbers need to be stored in international format?
When a recipient replies to one of your messages, it's received by Pendula in this format (we support SMS from all over the world). Therefore, for Pendula to match this message back to the correct contact record in your data source they need to be stored in this format.
Correct Format: +61400123456
Incorrect Format: 0400 123 456 or 0400123456

Understanding SMS Segmentation and Concatenation

The most effective SMS content is relevant, interesting and easily understood. It's designed for sending short messages which are rapidly delivered, with a high read and response rate.


SMS messages are typically restricted to 160 characters. When your message exceeds this limit, it must be segmented. Each segmented part of the message can hold 153 characters, not the full 160, because additional characters are needed to manage and reassemble the message parts correctly on the recipient's device. Aim to communicate your message within the standard SMS length of 160 characters. This limit keeps the message concise enough for quick consumption without needing segmentation.


This is the process of linking segmented messages so that they appear as a single, continuous message on the recipient’s phone. This is done automatically by most modern mobile devices, which recognise the segments and stitch them together seamlessly.

This message is exactly 160 characters, fitting within one SMS segment.

  Quick reminder: Your appointment is scheduled for tomorrow at 3 PM. Please reply
  YES to confirm or NO to reschedule.

This message is 290 characters, which would be split into two segments. The first segment uses 153 characters, and the remaining 137 characters form the second segment.

  Thank you for your recent purchase from our store! We hope you are delighted
  with your new items. Remember, if you have any questions or need support, don't
  hesitate to contact our customer service team. We're here to help!

If your message strategy involves longer narratives, consider how smartphones and carrier limitations might affect the delivery. Keep your messages below 750 characters (approximately 5 concatenated segments) to ensure compatibility and delivery across all devices and networks.

Managing non-GSM characters in SMS

When incorporating non-GSM characters—such as emojis or characters from non-Latin scripts—into SMS messages, understanding their impact on segmentation and encoding is important

Typically, SMS messages use the GSM-7 character set, including letters, numbers, and common punctuation, each encoded in 7 bits, allowing up to 160 characters per SMS.

Non-GSM characters require UCS-2 encoding, which uses 16 bits per character. This change reduces the maximum length to 70 characters per SMS. Each segmented SMS can then only contain 64 characters due to the additional space needed for headers. Non-GSM characters, like emojis, often consume more space than GSM characters. Most emojis count as two characters, but newer ones might take up to four. Messages with non-GSM characters are segmented when they exceed 70 characters, with each segment able to contain only 64 characters. This needs careful management to avoid unexpected costs and message fragmentation.

For a detailed guide on non-GSM characters, see Understanding non-GSM characters.

Pendula helps you identify when a non-GSM character is introduced to your intended messaging.

Stick to the GSM-7 character set, which include letters of the English alphabet, numbers, and common punctuation marks or symbols such as !,'@%$=.?/().. Avoiding characters outside this set ensures that your message remains within the single SMS limit and avoids potential delivery issues.

Certain symbols, like curly brackets {} or the Euro symbol , consume more than one character space. Using these sparingly can prevent unexpected message segmentation.

Keep your messaging relevant and valuable to your customers

To maintain customer interest and satisfaction, it is essential to ensure that every SMS sent holds significance for its recipients. Irrelevant messages not only disrupt the customer but also increase the likelihood of them perceiving the communication as spam.

Merge fields act as placeholders within your SMS template, which are automatically filled with specific data from your database when messages are sent. You can use a recipient’s first name to address them directly in the SMS, making the message feel more personal and engaging.

  "Hi {{First Name}}, don't forget your appointment on **{{Appointment Date}}**
  at {{Time}}. Reply YES to confirm."

For a detailed guide on Merge Fields, see Working with Merge Fields in Workflow Studio

Limit your CTA to one or two options

Ensure your call to action is clear and straightforward, so recipients aren't confused on how they are supposed to respond. Providing too many different reply options increases the margin for error and generally makes for a worse experience. If there is a lot of information you wish to capture via SMS, consider breaking this up over a series of messages with a question and answer approach for a seamless and easy to follow conversation.

"To confirm your appointment, reply YES. For rescheduling, reply NO."

If the interaction requires more detailed responses or multiple pieces of information, consider deploying a series of messages, each with a clear, actionable step. This approach helps maintain engagement without overwhelming the recipient.

Keep inbound responses unique

In SMS communication, the context of a response is primarily discerned from the sender's mobile phone number and the message content. This direct and straightforward method differs from channels like email, where additional metadata can provide context.

Pendula allows for the automation of SMS-based conversations by setting specific expected responses to sent messages. If a response from a recipient perfectly matches a predefined expectation, automated actions can be triggered accordingly. To ensure clarity and effectiveness in automated SMS interactions, it's critical to designate unique response triggers for different messaging campaigns. When multiple messages request the same response, it can lead to confusion about which message the recipient is responding to. For instance, if two promotions are sent to the same contact and both anticipate a 'YES' reply, it will be unclear which promotion the 'YES' refers to.

Instead of using a generic reply like 'YES' for multiple offers, tailor the responses to be distinct:

"Reply YESDEAL to accept the 20% discount offer."
"Reply YESTICKET to confirm your event ticket purchase."
  • Use specific keywords that relate directly to the message content, reducing the likelihood of overlap and ensuring responses can be accurately matched to the correct interaction.
  • Communicate clearly in the SMS what the expected response should be, using straightforward language that ties directly back to the message's call to action.

Pendula SMS capabilities

Reply matching

Pendula's reply matching feature automates SMS responses by recognising specific keywords in incoming messages. This allows for predefined actions to be triggered based on customer replies, streamlining interactions and ensuring timely, relevant communications. For example, responses to promotional SMS such as "YES" to accept an offer or "NO" to opt out can automatically initiate appropriate follow-up actions, enhancing efficiency and customer engagement.

For further information, see How reply matching works

Rules and recipes

Rules allow you to define conditions for acceptable replies, such as specific keywords or formats. This helps in tailoring responses that trigger specific actions within your SMS workflows. Recipes are predefined rules that simplify setup by providing common response patterns. This makes it easier to quickly deploy interaction scenarios without crafting conditions from scratch.

For further information, see Rules and recipes

Nodes for SMS management

Inbound message trigger node

Initiates a flow when a specific SMS message is received. It is configured to recognise predefined keywords or phrases within the text message, facilitating instantaneous engagement with customers.

For further information, see Inbound message trigger node

Conversation action node

Handles two-way SMS interactions, enabling conversations that can adapt based on customer responses.

For a detailed guide, see Conversation node

Outbound SMS node

Sends a single SMS to a designated recipient. The node offers two outcome paths based on message delivery status—sent and not sent. It handles fallbacks and failures by tailoring experiences based on these outcomes.

For a detailed guide, see Outbound SMS

Workflow action nodes

Workflow action nodes in Pendula enhance the flexibility and efficiency of SMS campaigns by allowing for dynamic responses based on evolving criteria. These nodes can re-evaluate conditions midway through a customer journey, segment recipients into tailored pathways, and integrate valuable feedback directly into your data systems. By orchestrating multiple interactions within a single flow, they effectively synchronize your SMS strategies with broader business processes. This functionality is crucial for adapting communication tactics based on progressing leads, or updating database records based on interactive customer responses.