SMS Validator API

Validate SMS-capable phone numbers -- mobile vs landline detection, carrier type, E.164 format, SMS readiness. Pay-per-call via x402 (USDC on Base L2) -- no API key, no signup, no rate-limit wall.

Part of the klymax402 marketplace -- 100 x402 micropayment APIs for AI agents, one wallet, USDC on Base.

Quickstart -- MCP

Add to your MCP client config (Claude Desktop, Cursor, ElizaOS, etc.):

config.json

{
  "mcpServers": {
    "sms-validator": {
      "url": "https://sms-validator.api.klymax402.com/mcp"
    }
  }
}

Quickstart -- HTTP (x402)

Terminal

curl -X POST "https://sms-validator.api.klymax402.com/api/validate" \
  -H "Content-Type: application/json" \
  -d '{"phone":"..."}'
# -> 402 Payment Required, with an x402 payment challenge in the response body

Any x402-aware client (@x402/fetch, x402-agent-tools, ATXP) handles the 402 -> sign -> retry cycle automatically.

Tools

Tool	Method	Path	Price	Description
`sms_validate_number`	POST	`/api/validate`	$0.005	Validate if a phone number can receive SMS

`sms_validate_number`

Use this when you need to check if a phone number can receive SMS messages. Returns SMS capability data in JSON.

Parameters

Name	Type	Required	Description
`phone`	string	yes	Phone number with country code (e.g. +14155551234)
`countryCode`	string	no	ISO 3166-1 alpha-2 country code hint (e.g. US, FR, GB)

Example response:

config.json

{"phone":"+14155551234","canReceiveSMS":true,"carrierType":"mobile","e164":"+14155551234","countryCode":"US","numberType":"mobile","carrier":"T-Mobile"}

When to use: sending SMS campaigns, FOR filtering landlines from SMS lists, verifying 2FA phone numbers, and OTP delivery validation.

Not for: full phone validation with carrier lookup (use phone_validate_number), email validation (use email_verify_address), address validation (use address_validate).

Example agent prompts

"Check if a phone number can receive SMS messages"

Payment

Protocol: x402 -- HTTP-native pay-per-call, no signup, no API key
Network: Base L2 (eip155:8453)
Asset: USDC
Facilitator: Coinbase CDP (primary), PayAI (fallback)
Also reachable via ATXP (OAuth-wrapped x402, RFC 9728 protected-resource metadata)

Part of klymax402

100 x402 micropayment APIs for AI agents -- one wallet, USDC on Base, zero signup.

Catalog: https://klymax402.com/llms.txt
Full API reference: https://klymax402.com/llms-full.txt
Live stats: https://klymax402.com/stats

License

MIT