SMS and WhatsApp for AI agents
KaiCalls lets an AI agent send and receive texts from its own phone number and reply on a connected WhatsApp number, through one MCP server or REST API.
New conversations can route straight to your agent, and a person can take a conversation over at any time. Your agent hears about every reply as an event.
Texting from the agent’s number
Texts go out from the same number the agent calls from, so a customer who replies lands back in the same conversation. Incoming texts reach your agent as events.
US carriers require business texting to be registered. Registration runs through the same connection, and the server will not send on a line that is not ready.
Connect the business’s WhatsApp number once. After that your agent can reply to a customer who messaged that number in the last 24 hours, which is WhatsApp’s own rule for business messages.
Routing and handoff
Connect your agent to a business and new text and WhatsApp conversations route to it. An explicit handoff always wins, so the owner or a teammate can take a conversation and give it back.
- Consent, do-not-call, quiet hours and rate limits are checked on every send
- A refused send says which rule blocked it
- Every event is signed and carries your own reference
Tools for texting
| Tool | What it does |
|---|---|
send_sms | Send a text from one of the agent’s lines |
send_message | Send on the channel you choose: SMS or WhatsApp |
list_sms_messages | Read the text history |
connect_whatsapp | Connect a WhatsApp business number |
get_channel_status | Check which channels are ready to send |
connect_agent | Route new conversations to your external agent |
set_conversation_owner | Hand a conversation to a person or back |
submit_text_registration | Register the business for texting |
The same tools are on the MCP server, the REST API and the Python SDK.
Questions
- Can an AI agent send text messages?
- Yes. With KaiCalls an agent texts from its own US number, receives replies as events, and the server checks consent, quiet hours and rate limits on every send.
- Can an AI agent use WhatsApp?
- Yes, on a WhatsApp number the business connects. The agent can reply to a customer who messaged that number in the last 24 hours, which follows WhatsApp’s rules for business messages.
- Can a person take over a text conversation?
- Yes. Set the conversation’s owner to a person and the agent steps back. Hand it back the same way.
- Do I need to register for business texting?
- For US numbers, yes. Carriers require it. KaiCalls runs the registration through the same connection and tells you when the line is ready to send.