Developer guide
Know what a line type result actually means.
A line type lookup classifies a phone number, for example as mobile, fixed line, VoIP, or toll-free. QuietPass’s free basic line type uses numbering-plan metadata. Enhanced number-level line type is a separate optional layer and is not connected yet.
Basic line type versus enhanced line type
basic_line_type uses the number’s published numbering range. It can return a classification or an ambiguous or unknown result. It is free and does not verify a serving network after number porting.
enhanced_line_type is reserved for richer supplier data. Supplier definitions and country coverage must be checked before relying on distinctions such as fixed versus non-fixed VoIP. QuietPass currently returns an unavailable result for this layer; it does not infer that missing data means “mobile.”
Can line type confirm SMS capability?
No. A mobile classification is useful input, but delivery and number ownership require separate checks. Fixed-line-or-mobile and unknown classifications must remain explicit. QuietPass currently restricts its onboarding SMS candidates to numbers classified as mobile and applies destination and cost controls before sending. SMS onboarding itself is not yet enabled.
Request basic type without a paid lookup
{
"phone": "YOUR_VERIFIED_NUMBER",
"checks": ["basic_line_type"]
}Read checks.basic_line_type.status before using its type value. For example, an unavailable classification needs different handling from a completed mobile result. Formatting and validation still run first.
Use classifications as inputs, not verdicts
For a contact form, a type result can help choose the next verification step. For list preparation, it can separate known categories from numbers that need review. It cannot establish that a person is genuine, that a VoIP number is fraudulent, or that a mobile number is safe.
Review the coverage and capability table before planning an integration. If you need the serving network after porting, see carrier lookup and MNP.
Background: Google libphonenumber FAQ. QuietPass uses the separate JavaScript library libphonenumber-js with full metadata.