--- title: "What STIR/SHAKEN obligations apply to white-label softphone operators?" topic: "Compliance & Legal" updated: 2026-07-09 canonical: https://acrobits.net/resources/knowledge-base/stir-shaken-white-label/ summary: "In a white-label softphone setup, the SIP trunk provider is responsible for STIR/SHAKEN attestation, not the app or the operator. The originating carrier holds the signing certificate and attaches an attestation to every outbound call, which determines whether receiving carriers let it through or flag it as \"Spam Likely.\" If subscribers see spam labels or dropped calls, the fix sits with the trunk provider's STIR/SHAKEN compliance, not the softphone app." --- # What STIR/SHAKEN obligations apply to white-label softphone operators? > In a white-label softphone setup, the SIP trunk provider is responsible for STIR/SHAKEN attestation, not the app or the operator. The originating carrier holds the signing certificate and attaches an attestation to every outbound call, which determines whether receiving carriers let it through or flag it as "Spam Likely." If subscribers see spam labels or dropped calls, the fix sits with the trunk provider's STIR/SHAKEN compliance, not the softphone app. In a white-label softphone setup, the SIP trunk provider is responsible for STIR/SHAKEN attestation, not the app or the operator. The originating carrier holds the signing certificate and attaches an attestation to every outbound call, which determines whether receiving carriers let it through or flag it as "Spam Likely." If subscribers see spam labels or dropped calls, the fix sits with the trunk provider's STIR/SHAKEN compliance, not the softphone app. ## What STIR/SHAKEN does STIR/SHAKEN is a caller ID authentication framework mandated by the FCC since June 2021. It works like a digital signature for phone calls. When a call is placed, the originating carrier cryptographically signs it with an attestation level: AttestationMeaningImpact on Delivery **Full (A)**Carrier verified the caller's identity and their right to use that numberCalls go through normally **Partial (B)**Carrier verified the caller but not their right to that specific numberMay trigger warnings on some devices **Gateway (C)**Carrier received the call from an international gateway or can't verify the callerFrequently flagged or blocked **None**No signature attachedIncreasingly blocked by receiving carriers The receiving carrier checks the signature. If it's missing or low-level, the call gets flagged, labeled as spam, or silently dropped. Many carriers are tightening spam detection and call analytics. ## Who signs the call in a white-label setup? **In a white-label setup, the SIP trunk provider signs outbound calls, not the softphone operator.** Neither the app nor the white-label vendor applies the signature. The originating carrier (your SIP trunk provider) holds the certificate, applies the signature, and determines the attestation level on every outbound call. Your softphone app is a client. It sends SIP INVITE messages to your trunk provider's infrastructure. From there, your trunk provider originates the call into the PSTN and attaches the attestation. If the trunk provider is not STIR/SHAKEN-compliant, outbound calls may be labeled or blocked. ## What to verify with your trunk provider Before signing a trunk agreement, or if you're already seeing spam flags, ask these questions: **1. Are you registered in the STI-PA database?** Every carrier that signs calls must be registered with the Secure Telephone Identity Policy Administrator. You can check the [FCC Robocall Mitigation Database](https://fccprod.servicenowservices.com/rmd) yourself. **2. What attestation level do my calls receive?** Full (A) attestation is generally the target for outbound calls when the provider can support it. If your trunk provider can only offer Partial (B) or Gateway (C), your calls will be treated as lower trust by receiving carriers. **3. Do you support number validation for my [DIDs](/voip-glossary/did/)?** Full attestation requires that the trunk provider can confirm your right to use each number. If you bring your own numbers (LNP/ported), make sure the provider's system recognizes them. **4. What happens if attestation fails?** Some providers fall back silently to unsigned calls. Others reject the call. Know which behavior you're getting. **5. Do you have a SHAKEN certificate from an approved CA?** The certificate must come from an STI-approved Certificate Authority. Some providers have not completed this step, including some smaller regional carriers. ## Where Cloud Softphone fits in STIR/SHAKEN Cloud Softphone operates at the application layer. It handles SIP registration, call setup, audio/video, and push notifications. When a user dials a number, the app sends a standard SIP INVITE to whatever SIP infrastructure you've configured. Cloud Softphone passes through the caller ID exactly as configured in your provisioning. It doesn't modify, strip, or inject caller ID information. It doesn't touch STIR/SHAKEN attestation because that process happens downstream at the trunk level. The app passes caller ID through and leaves STIR/SHAKEN attestation to the trunk provider, which is where the signing authority sits. ## What operators should do next If you're launching a branded softphone service, STIR/SHAKEN compliance is a trunk-side checklist item, not an app-side one. But ignoring it means your subscribers' calls get flagged, and they'll blame your app. Three steps to protect your service: - **Audit your trunk provider** using the questions above. Verify their STI-PA registration. - **Test outbound calls** to major carriers (AT&T, T-Mobile, Verizon) and check whether your number shows as verified or flagged. - **Monitor ongoing attestation.** Trunk providers can lose compliance status, so consider a quarterly compliance check in your operations. Verify your trunk provider's STIR/SHAKEN attestation before launch so your subscribers' outbound calls stay trusted at the carrier level. *To keep attestation on the trunk side where it belongs, [learn how Cloud Softphone integrates with your existing SIP infrastructure](/cloud-softphone/).* STIR/SHAKEN is one of several obligations that attach when you add voice; the related [E911 and legal requirements for ISPs adding voice](/blog/cloud-softphone/e911-legal-isp-voice/) activate at the same time. { "@context": "https://schema.org", "@type": "Article", "headline": "STIR/SHAKEN Obligations for White-Label Softphone Operators", "description": "In a white-label softphone setup, the SIP trunk provider is responsible for STIR/SHAKEN attestation, not the app or the operator. The originating carrier holds the signing certificate and attaches an attestation to every outbound call, which determines whether receiving carriers let it through or flag it as \"Spam Likely.\" If subscribers see spam labels or dropped calls, the fix sits with the trunk provider's STIR/SHAKEN compliance, not the softphone app.", "url": "https://acrobits.net/blog/cloud-softphone/stir-shaken-white-label/", "datePublished": "2026-05-06T09:00:00Z", "dateModified": "2026-05-06T09:00:00Z", "author": { "@type": "Organization", "name": "Acrobits" }, "publisher": { "@type": "Organization", "name": "Acrobits", "url": "https://acrobits.net" } }