SMS

SMS is the most universally reliable messaging channel available. It works on every phone, in every country, with no internet connection required.

When to use SMS

• OTPs and verification codes: 98% open rates make SMS the best channel for time-sensitive authentication
• Critical alerts: delivery notifications, fraud warnings, emergency communications
• Users without your app: SMS reaches anyone with a phone number
• Areas with limited connectivity: SMS works on 2G networks and during internet outages

Sending an SMS

curl -X POST https://api.smooven.io/v1/agent/notify \
  -H "Authorization: Bearer YOUR_SECRET_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "channel": "sms",
    "to": "+61400000000",
    "message": "Your verification code is 482910. It expires in 5 minutes."
  }'

Request parameters

Parameter	Type	Required	Description
channel	string	Yes	Set to "sms"
to	string	Yes	Recipient phone number in E.164 format (e.g., +61400000000)
message	string	Yes	Message content (max 1600 characters, automatically segmented)
sender_id	string	No	Custom sender ID or short code
callback_url	string	No	Webhook URL for delivery status updates

Message segmentation

SMS messages longer than 160 characters are automatically split into multiple segments. Each segment counts as a separate message for billing purposes.

Character set	Segment length
GSM-7 (standard Latin)	160 characters
Unicode (emoji, CJK)	70 characters
Concatenated GSM-7	153 characters per segment
Concatenated Unicode	67 characters per segment

Delivery status

Smooven tracks SMS delivery through carrier networks. Possible status values:

• queued: message accepted and in queue
• sent: message handed off to carrier
• delivered: carrier confirmed delivery to handset
• failed: delivery failed (invalid number, carrier rejection, etc.)
• undelivered: carrier could not reach the handset after retry attempts

Pricing

SMS pricing varies by destination country. See the pricing page for current rates. All plans include a free message allocation each month.

Best practices

1. Keep messages concise. SMS is best for short, actionable content.
2. Include opt-out instructions for marketing messages (regulatory requirement in most regions).
3. Use E.164 format for phone numbers to avoid routing errors.
4. Set up webhooks to track delivery and handle failures gracefully.
5. Consider fallback channels. Use Smart Routing to automatically fall back to push or email if SMS fails.