Platforms: SMS / Twilio

While Dexter's other platforms such as Facebook or Twitter offer power in the expressiveness of what you can do with them (e.g., prompting users with buttons), SMS's power lies in its ubiquity. You can pretty much count on your audience being on SMS.

Follow the step-by-step instructions found on the Platform configuration page to get started with deploying and launching a bot on SMS (you will create an account on a service called Twilio to do this, and take a look below for some detailed descriptions on concepts.


If a user ever messages your bot with language like "unsubscribe" or "stop," Twilio automatically handles the mechanism for you. Read more about how this works.

Twilio Messaging & Broadcast Policies

All broadcasts you send via Twilio must conform to their policies around messaging.

Twilio does not allow you to use their service to send spam, send harassing or abusive messages, engage in fraud or phishing, misrepresent your identity, or send pornographic or objectionable images. Learn more about Twilio's messaging policies here.


How can I debug my Twilio message / error?

For resources on understanding Twilio errors:

  1. Look at the Logs of your bot editor.
  2. Venture over to the Twilio Phone Numbers page after logging into your Twilio account. Find your relevant phone number and explore the Messages Log.

Sample Twilio Message Log

How much does it cost to use Twilio?

Twilio is an SMS platform that will accrue costs with continued usage. To use Twilio, you may use the provided trial number and trial account with Dexter, but the usage of these trial credentials will be rate-limited by Twilio. Your total invoice may vary depending on the phone numebr you choose to purchase and the number of messages your bot receives and sends. You can read more about fees associated with using Twilio on their pricing page.

I am the only user receiving messages from the bot. When other users message my Twilio number, there is no response.

You may be using a Twilio free trial. This trial account can be used with any Dexter bot, but you must verify any non-Twilio phone numbers -- add them to your phone number -- before sending or receiving any SMS messages to/from it. Read more about Twilio's Free Trial.

Twilio has flagged me for sending a high volume of messages over a 10-digit number.

Twilio does not support broadcasting marketing messages from a long-code (10-digit number). With the free subscription, you may send broadcasts to less than 100 unique recipients through the long-code. Marketing messages can only be sent using shortcodes. Learn more about shortcodes here.

My SMS messages are not arriving in the right order.

Send/delay work very well in our system! However, once they reach Twilio - or, to be more precise, the telecom providers Twilio sends the information to - all bets are off. Twilio describes the problem and notes a semi-solution here. Increasing your delay MAY help, but there's sadly no way to ensure response order via SMS. Message order may vary depending on carrier.

My media files are not coming through on Twilio.

Total message size must be under 5MB. Twilio recommends keeping content size for each piece of media under 500KB. You can confirm if your message has succeeded or failed in sending by visiting the Message Log of your phone number on the Twilio console.

My carrier splits up my messages into multiple messages, what should I do?

Certain carries -- ahem, Sprint -- will split long messages (over 160 characters) instead of showing them as a single message, message order not guaranteed. Strategies for combatting this include purchasing a Twilio shortcode (5-digit number) to message from, or to send only MMS messages (messages with media embedded) instead of PlainText SMS messages.

How do I send a vcf file?

Upload your vcf file and provide the url as a parameter into the ^file() shortcode.