Skip to content
Book a demoStart free trial (opens in a new tab)
Start free trial (opens in a new tab)Book a demo
Docs

SMS campaigns with Retell AI

An SMS campaign texts every contact on a list from your client’s own number. A Retell AI chat agent writes each first message using the contact’s details, sends it, and carries on the conversation when the contact replies. Use it for reminders, follow-ups and re-engagement where a text suits better than a call. SMS campaigns are for clients whose agents run on Retell AI.

Before you begin

Section titled “Before you begin”
  • A Retell AI client with its API key in the portal. See Connect Retell AI.
  • A number with SMS turned on in Retell AI: a number bought from Retell AI, or one imported into Retell AI with SMS enabled. In the US, sending business texts also needs A2P 10DLC registration for the number.
  • A Retell AI chat agent. Voice agents can’t send texts. Note its agent ID (it starts with agent_).
  • The chat agent’s prompt using the contact details you pass, for example {{name}} and {{meeting_date}}, and {{campaign_notes}} for the notes clients add when launching.

Set it up

Section titled “Set it up”

  1. Create the playbook

    In Campaign playbooks, select New playbook and choose SMS. Set the details each contact needs, the tries, the hours and the pace. See Campaign playbooks.

  2. Assign it to the client

    Select Assign on the client’s row and enter the SMS number in international form, for example +14155550123, and the Retell chat agent ID. Select Save. The row shows Ready, or “SMS campaigns need a Retell client” if the client uses another provider.

  3. Send yourself a test

    Select Test as client, choose the playbook, pick a list, and on the What step use Send me a test with your own mobile number. The chat agent writes and sends the first text.

What happens for each contact?

Section titled “What happens for each contact?”

The portal asks Retell AI to start a chat from the client’s SMS number with the chat agent and the contact’s details. The agent writes and sends the first text; replies go to the same agent. Each text counts as an attempt on the campaign page. Contacts on Retell AI’s own do-not-call list are refused by Retell AI, and contacts marked Do not call in the portal are never texted.

SMS uses the client’s chats under client billing, like WhatsApp messages.

Troubleshooting

Section titled “Troubleshooting”
Problem What to do
“Retell refused the test SMS: Item not found in a2p-application …” The number isn’t registered for SMS in Retell AI. Turn on SMS for the number in Retell AI (including A2P 10DLC registration for US numbers), then try again.
The campaign shows Paused: setup problem Retell AI refused something every text would hit: the number, the agent, the API key or the account’s credit. The banner shows Retell AI’s message. Fix it, then select Resume.
A contact shows “Retell refused the SMS …” Retell AI refused that one contact, for example an invalid number or one on its do-not-call list. The campaign carries on with the others.
Texts are slow to go out Retell AI asked the portal to slow down, or had a temporary problem. The portal tries again on the next run, within a minute.
The first text doesn’t use the contact’s details Check the chat agent’s prompt uses the same names as the playbook’s details, for example {{meeting_date}}.
Section titled “Related”