Serving US-destined voice traffic carries a regulatory burden that international-only routes simply don't have. A carrier that terminates calls exclusively to European or Asian destinations answers to a completely different set of rules than one carrying traffic to US phone numbers.
For businesses evaluating a wholesale voice provider for US traffic, the regulatory question is often more consequential than the rate card. A provider that cannot demonstrate proper FCC registration, STIR/SHAKEN attestation, and 911 compliance isn't just a compliance risk on paper — it can mean calls get mislabeled as spam, traffic gets blocked by downstream carriers, or your business inherits liability it never signed up for.
This guide focuses specifically on the US regulatory and compliance landscape for wholesale voice termination: what STIR/SHAKEN attestation levels mean, what the FCC's Robocall Mitigation Database requires, how E911 obligations under Kari's Law and RAY BAUM'S Act apply to voice providers, and what documentation you should ask a provider to produce before committing traffic to them.
STIR/SHAKEN is the caller ID authentication framework the FCC has required US voice service providers to implement, built to combat illegal caller ID spoofing that fueled the robocall epidemic. Under the framework, the provider that originates a call cryptographically signs it with an attestation level, and that signature travels with the call so the terminating carrier can verify it. Frameworks like this build on core signaling standards such as SIP (RFC 3261), which defines how call setup information is carried across IP voice networks.
Full Attestation (A) means the originating provider has authenticated the caller, confirmed the caller is authorized to use the calling number, and can vouch for the entire call. Partial Attestation (B) means the provider authenticated the customer originating the call but cannot confirm the customer is authorized to use that specific number — common for calls entering the network from a customer the carrier has verified but not fully validated on number ownership. Gateway Attestation (C) applies when a provider receives a call from outside its own network (for example, an international gateway) and cannot verify the origin at all, only that it accepted the call for further routing.
For wholesale voice traffic terminating to US numbers, attestation level has practical consequences: calls carrying lower attestation, or none at all, are increasingly subject to call-blocking or "Spam Likely" labeling by terminating mobile carriers, regardless of whether the call is legitimate business traffic.
Attestation level isn't just a compliance checkbox — it directly shapes whether your calls actually get answered. Terminating mobile carriers use attestation as one of the strongest signals in their spam-filtering models, so a drop from Full to Partial or Gateway attestation can measurably reduce answer rates even when nothing else about the call has changed.
Because attestation is only one input into deliverability, it's worth evaluating a provider's overall route quality alongside it — reading ASR, PDD, and CLI data covers the metrics that, together with attestation, determine whether your US-bound calls actually connect.
The TRACED Act directed the FCC to build out the regulatory infrastructure behind STIR/SHAKEN enforcement, and one of the resulting requirements is that voice service providers file information with the FCC's Robocall Mitigation Database (RMD). This filing generally covers whether the provider has implemented STIR/SHAKEN across its network, and if not, what alternative robocall mitigation practices it has in place instead.
A key enforcement mechanism tied to this database is that intermediate and terminating providers are expected to reject traffic from providers that are not listed in the RMD. In practice, that means a wholesale voice provider without a current, accurate RMD filing risks having its traffic blocked further down the call path — a risk that gets passed on to any business routing calls through that provider.
Kari's Law requires that multi-line telephone systems allow users to dial 911 directly, without needing to dial a prefix first, and that the system notify a designated person or location on-site when a 911 call is placed. This obligation sits primarily with the equipment and system configuration, but any voice provider supporting MLTS deployments for US customers needs to ensure its platform doesn't interfere with direct 911 dialing.