Avicenna supports sending notifications to participants and researchers via SMS in addition to in-app and email channels. Because SMS messages are delivered through an external telecommunications provider, enabling SMS for a study introduces additional charges that do not apply to in-app or email notifications. This page explains how those charges are calculated, so you can estimate the cost of SMS for your study in advance.
How Avicenna Sends SMS Messages
Avicenna does not operate its own cellular network. SMS messages from the platform are sent through Twilio, a third-party messaging provider. The cost passed on to your study is the cost Twilio charges Avicenna for delivering each message, with no additional markup.
This means the SMS cost for your study depends entirely on Twilio’s published rates for the destination country, the type of phone number used, and the length of each message.
What Determines the Cost of a Message
Three factors determine the cost of a single SMS notification:
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Destination country. Twilio charges a different per-message rate for each country. Messages sent to participants in Canada or the United States are typically inexpensive, while messages to some other countries can be several times higher. The current per-country rates are listed on Twilio’s SMS Pricing page.
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Message length. SMS messages are billed in segments. A single segment is 160 characters for standard GSM-7 messages, or 70 characters when the message includes non-GSM characters such as emojis or certain Unicode symbols. Longer messages are split into multiple segments, and each segment is billed separately. A 200-character GSM-7 message, for example, is billed as two segments.
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Sender type. Depending on the destination country, messages may be sent from a long code, short code, or alphanumeric sender ID. The rates for each sender type are also listed on the Twilio pricing page.
In addition to per-message charges, Twilio applies a small monthly fee for any phone numbers leased to send messages. This fee is included in the SMS charges passed on to your study.
Estimating the SMS Cost of a Study
To estimate the total SMS cost, you can use the following formula for each destination country:
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Number of participants expected to opt in to SMS notifications.
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Number of SMS notifications each participant will receive over the course of the study (for example, one daily reminder for 30 days is 30 messages).
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Average number of segments per message, based on the length and character set of your notification templates.
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The per-segment rate for the destination country, taken from Twilio’s SMS Pricing page.
The product of these four numbers is a close estimate of the total SMS cost for the study. If your participants are distributed across multiple countries, repeat the calculation for each country and sum the results.
Enabling SMS for Your Study
SMS notifications are not enabled by default. To enable them for a study, contact Avicenna Support. When you reach out, it is helpful to share the expected participant countries and the approximate number of messages per participant, so support can confirm the rates that will apply and help you plan accordingly.
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Recipients also need to verify their phone numbers before they can receive SMS notifications. Depending on their mobile plan, participants may be charged by their carrier for receiving messages. This is separate from the per-message cost billed through Twilio.