SMS
SMS units
How the SMS wallet works — 1 unit pays for 1 SMS part.
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Your organisation's SMS wallet holds units. One unit pays for one SMS part. The API reports everything in units — it never shows prices.
You buy units in the app (SMS → Wallet). The price per unit depends on how many you buy; see pricing.
How many parts is my message?
| Message length | Parts (units per recipient) |
|---|---|
| Up to 160 characters | 1 |
| 161 – 306 characters | 2 |
| 307 – 459 characters | 3 |
| Longer | 1 part per 153 characters, rounded up |
Longer messages are split into 153-character parts because each part carries a few characters of joining information. The maximum message length is 1,600 characters.
Special characters
Part counts assume the standard GSM character set (letters, numbers, common punctuation). Emoji and some special characters can make a network split a message into more, shorter parts. Keep messages to plain text where possible.
Units in API responses
| Field | Where | Meaning |
|---|---|---|
units_available | balance, send, batch receipt | Units left in the wallet |
sms_parts | send, status, batch | Parts (units) for that message |
units_used | send (up to 50 numbers) | Units used by this request |
units_required | batch receipt (51+ numbers) | Units the batch will use |
When are units used?
- Units are used when a message is handed to the network.
- Numbers that have opted out are skipped and use no units.
- Before sending, CloudMetis checks you have enough units for the whole request. If not, nothing is sent and you get
402 insufficient_units. - Sandbox (test key) messages never use units.