Chat

SMS

Run the same agent over text messaging. SMS is the highest-response channel Katexs supports and the most heavily regulated — the setup below covers both halves.

Enable SMS on a number

1
Choose an SMS-capable number
In Settings → Phone Numbers, check the SMS column. Toll-free and local numbers both work; imported numbers must have messaging enabled at the carrier.
2
Register the number
US traffic requires brand and campaign registration. Submit your business details in Settings → Phone Numbers → Messaging. Approval typically takes one to three business days.
3
Attach an agent
Select the agent that should answer texts. Voice and SMS can share one agent or use separate ones.
4
Send a test
Text the number from your own phone. The thread appears in Data → Call Logs with channel sms.

Unregistered US traffic is filtered by carriers, not by Katexs. Messages may appear sent while never arriving. Complete registration before any campaign.

How SMS conversations behave

Sessions are longer — The default SMS inactivity window is 12 hours, because people reply to texts on their own schedule.
Segments cost money — Every 160 GSM-7 characters is one segment; a single emoji drops the limit to 70. Instruct the agent to keep replies under two segments.
No interruption model — Turns are discrete. If a customer sends three messages quickly, the agent receives them batched as one turn.
Media — Inbound images are accepted on MMS-capable numbers and passed to the agent as attachments when vision is enabled.

Opt-in

You may only message people who agreed to be messaged. Katexs records consent on the contact so an audit can be answered with a timestamp and a source, not a memory.

Consent type	How it is captured	What it permits
Inbound-initiated	The customer texts you first	Replies within the conversation window
Written express	Checkbox at signup, recorded via API	Transactional and promotional, per your disclosure
Verbal on a call	Agent asks and confirms; stored with recording reference	As disclosed during the call

bash

curl -X POST https://api.katexs.com/v1/contacts/consent \
  -H "Authorization: Bearer $KATEXS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "phone": "+15555550142",
    "channel": "sms",
    "status": "opted_in",
    "source": "checkout_form_v3",
    "captured_at": "2026-08-02T14:11:09Z",
    "disclosure": "Msg & data rates may apply. Reply STOP to opt out."
  }'

Opt-out

Katexs intercepts standard opt-out keywords before the agent sees the message, marks the contact do-not-contact for the SMS channel, and sends a single confirmation. This is automatic and cannot be disabled.

Keyword	Effect
STOP, STOPALL, UNSUBSCRIBE, CANCEL, END, QUIT	Immediate suppression plus one confirmation message
START, UNSTOP, YES	Resubscribes a previously suppressed contact
HELP, INFO	Returns your configured help text with business name and contact

Suppression is per channel. Someone who opts out of texts can still be called if you hold valid consent for voice — but check your own policy before relying on that distinction.

Compliance checklist

Identify yourself — The first message in any outbound thread names your business.
Include opt-out language — At minimum in the first message of every campaign.
Respect quiet hours — Katexs blocks outbound SMS outside 8am–9pm in the recipient's local time by default.
Keep proof — Consent records and message logs are retained for the life of the contact and exportable on demand.
Set a help response — Required by carriers; configured in Settings → Phone Numbers → Messaging.

Campaign setup Security and privacy