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How do I Let Contacts Opt In by SMS? ​

Let people join a group by texting a code, such as JOIN, to your number, and leave by texting another, such as STOP. It's a simple way to grow a subscriber list with consent.

📖 Pre-requisites

  • A SIM hosted on Cecula Sync and registered in DartPro as an identity. People text your codes to this number.
  • A group to collect subscribers. See How do I Create a Group?.

Set Up Opt-In ​

  1. Open the Group

    • Click Groups in the left sidebar and open the group.

  2. Edit the Group

    • Click Edit Group. Set up opt-in here, after the group has been created.

  3. Turn On Subscription

    • Switch on Allow contacts to opt-in via SMS.
    • If No Hosted SIM Found appears, you need a hosted number first. See Getting a Hosted Number.

  4. Fill In the Subscription Settings

    • Hosted Number: the number people will text.
    • Opt-In Code: the word or number that joins the group, for example JOIN.
    • Opt-Out Code: the word or number that leaves the group, for example STOP.

  5. Save

    • Click Save. DartPro shows Group Updated.

What Subscribers Do ​

Share instructions such as: Text JOIN to 0803 000 0000 for our updates. Text STOP to leave.

When someone texts the opt-in code:

  • They're added to the group. If their number isn't in your contacts yet, DartPro creates a contact for it.
  • You get a notification such as 2348030000000 Joined Customers Group.

When someone texts the opt-out code:

  • They're removed from the group.
  • If they don't belong to any other group, their contact is deleted.
  • You get a notification such as 2348030000000 Left Customers Group.

How Codes Are Matched ​

  • The whole message must be the code. Spaces before or after are ignored, but JOIN NOW doesn't match JOIN.
  • Capital letters matter. join doesn't match JOIN, so tell subscribers exactly how to type it.
  • One number can serve several groups. Give each group its own codes. If two groups on the same number share a code, a subscriber joins or leaves both.

Getting a Hosted Number ​

The No Hosted SIM Found message explains your options:

  • You already host a SIM on Cecula Sync: sign in to get your API key, then click Register SIM to register the number in DartPro.
  • You don't have a hosted SIM: buy a SIM hosting plan on Cecula Sync, then follow the instructions to activate the SIM.

You can also pay for SIM hosting from the Sync Subscription tab on DartPro's Billing page.

Good Practice ​

  • Include your opt-out code in the messages you send, so subscribers always know how to leave.
  • Keep codes to one short word that's easy to spell.
  • Test your codes from your own phone before you publish them.