Three SMS modes
The same agent handles all three modes. What changes is who starts the conversation and whether replies are expected.Inbound (2-way)
Customer texts the agent number. Best for FAQ, account servicing, and queue callback replies from a live voice queue.
Outbound (2-way)
CRM event fires an HTTPS POST. Best for re-engagement, utility use cases, and status updates that expect a reply.
Triggered (1-way)
Agent sends via the
send_sms function in Agent Studio. Best for reminders, confirmations, OTPs, and post-call follow-up.Outbound and Triggered use the same webhook. Once a customer replies to an outbound message, the conversation routes automatically into the inbound flow with the same agent.
Key features
PolyAI-managed Twilio
PolyAI provisions and manages the Twilio infrastructure. No customer Twilio account is needed, and the agent phone number is provisioned in Agent Studio.Reuse your voice number
If PolyAI already handles your voice deployment, the same Twilio number serves both voice and inbound SMS. Once an SMS camapign has been approved by Twilio, you can also use the same number for outbound SMS.No extra number management.Unified conversation flow
SMS runs on the shared messaging architecture, so it inherits live agent handoff, CSAT, and events from voice and web chat. Multi-turn dialogue keeps context across the thread, and every conversation is visible in Agent Studio Conversation Review.Live agent handoff
Native handoff to Salesforce, Zendesk, NICE, Amazon Connect, and Webex. When the customer needs a person, the agent transfers the thread with full conversation context.Compliance and safety
- STOP/START/HELP keyword enforcement at the platform level (case-insensitive, tolerant of trailing punctuation).
- Opt-in and opt-out consent verification before send, with blocklist enforcement.
- Repeated-message detection and abuse auto-block.
- Per-sender and per-project rate limiting.
Operational control
Conversation lifecycle controls for inactivity timeout, end-of-conversation logic, and termination messaging. Failure logging and error visibility for every send.Templated and raw sends
Outbound supports raw and templated messages with variable injection, so CRM-triggered sends stay on brand and personalized.How it works
Inbound
1
Customer texts in
The customer texts the PolyAI agent number from their phone.
2
Twilio receives
Twilio fires a webhook to the PolyAI messaging service.
3
PolyAI compliance check
Rate limit, blocklist, and opt-in checks run before the message is accepted. A conversation record and session are created.
4
Agent conversation
The shared messaging architecture handles the turn, including handoff and CSAT events.
5
Reply sent
The agent reply is routed via Twilio back to the customer.
Outbound and Triggered
1
CRM event fires
Salesforce, Zendesk, Oracle, or Dynamics raises an event.
2
HTTPS POST
The CRM posts to the PolyAI outbound webhook with the recipient and message.
3
PolyAI compliance check
A specific agent number is selected. A conversation record and session are created.
4
Twilio delivers
Rate limit, blocklist, and opt-in checks run, then Twilio delivers the SMS.
5
Reply routes to inbound
If the customer replies, the reply lands in the standard inbound flow and the same agent picks up.
Setting up SMS
1
Provision the agent number
PolyAI provisions and manages the Twilio number in Agent Studio. If you already have PolyAI voice, the same number can serve inbound SMS.
2
Configure the SMS channel
Enable SMS on the agent in Agent Studio. Set the greeting, customise your styling prompt, and set channel specific configuration where required.
3
Register for compliance (US)
Complete 10DLC brand and campaign registration via Twilio. PolyAI handles platform-level keyword compliance. You manage consent records.
4
Wire your CRM (Outbound and Triggered)
Point your CRM at the PolyAI outbound webhook using a single HTTPS POST. Salesforce, Zendesk, Oracle (OIC / Eloqua), and Dynamics 365 are natively supported. Other CRMs work via Zapier middleware or a custom HTTPS POST.
5
Configure live agent handoff
Connect the CCaaS or ticketing platform your live agents work in (Salesforce, Zendesk, NICE, Amazon Connect, Webex).
6
Review conversations
Monitor traffic in Agent Studio Conversation Review. Filter SMS conversations using the
TW_SMS_ Call SID prefix.Compliance posture
Default rate limits
- Per-sender: 10 messages / 60 seconds. STOP/START/HELP keywords are exempt.
- Per-project: 100 messages / minute across all senders.
- Repeated-message auto-block: same message sent 5+ times in 5 minutes triggers a 10-minute auto-block that lifts automatically.
Use cases
FAQ and inbound support
Store hours, eligibility, and status checks. Highest volume, lowest complexity SMS traffic on the platform.
Queue callback and voice deflection
Deflect from a busy voice queue. Customers wait outside the queue while agents work down the backlog.
Appointment reminders and confirmations
Booking system fires a templated confirmation. Reschedule and cancel replies route to a live agent.
Post-call follow-up and surveys
Send a CSAT link or an open survey prompt after a voice call ends to capture feedback in the moment.
Order updates and delivery tracking
OMS or WMS fires status updates over SMS. Tracking questions route back to an inbound agent for resolution.
Re-engagement and lifecycle campaigns
Marketing CRM fires templated sends. Two-way replies route into the inbound agent flow for follow-up.
Outage and disruption alerts
Monitoring platform triggers alerts to affected customers. Cuts inbound voice volume on outage days.
Account alerts and fraud notifications
Banking or FS system triggers alerts with a one-tap reply flow for identity verification and dispute.
OTPs and auth confirmations
Fire-and-forget one-time passwords and authentication confirmations sent from Agent Studio functions.
Related pages
SMS API
Send outbound SMS messages through the PolyAI outbound webhook API.
Campaign registration (US)
10DLC brand and campaign registration requirements for US SMS traffic.
RCS
Rich, branded messaging over the RCS channel with SMS fallback.
Chat handoffs
CCaaS handoff integrations to transfer SMS threads to live agents.