Check Signal Registration
View All Signal Number Validation & Identity Lookup APIs →The lightest, fastest call: returns only whether a phone number is a registered Signal account, without fetching identity metadata. Ideal for real-time form validation, sign-up gating, and high-volume list screening. Pass the full international number (digits, optional leading +); the API normalizes to digits only. registered is three-state: true = registered, false = not registered, null = undetermined (transient — see message, e.g. timeout).
API Features
Real-time registration check Instantly know whether a phone number has a Signal account via a clear registered=true/false result
Lightweight & fast Returns only number + e164 + registered; no heavy identity payload, ideal for bulk pre-checks and sign-up gating
Three-state result registered can be true, false, or null (undetermined) with a message explaining transient failures
Normalized input Accepts the full international number with optional leading + and normalizes to digits
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GET
/api/project/signal/check API Response (JSON)
{} Query Result
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Use Cases
- Lead and contact validation: verify numbers are on Signal before outreach or enrichment
- Sign-up and onboarding gating: confirm Signal availability for channel selection
- List cleaning: bulk-check contact lists to flag non-Signal numbers
- Channel selection: pick the right outreach channel before sending a message or OTP