AI voice agents in the United States: TCPA, STIR/SHAKEN and the buyer landscape

Market shape

The United States is the market most voice-agent vendors build for first, so it is also where the vocabulary split is widest. A dental practice or a plumber searches for an AI receptionist or an AI answering service. A health system or a bank talks about voice agents, agentic customer service or contact center AI. The product is the same; the compliance checklist and the integration depth are not.

Five facts worth holding onto. First, market-size estimates disagree and neither is a measurement of your calls: MarketsandMarkets puts the global voice agents market at USD 2.32 billion in 2025 rising to USD 27.45 billion by 2032, with North America at USD 974 million in 2025 (report page as retrieved 1 October 2026); Astute Analytica puts the same market at USD 3.0 billion in 2025 rising to USD 45.1 billion by 2035 (page updated 20 July 2026). Second, Gartner's 5 March 2025 prediction that agentic AI will autonomously resolve 80 percent of common customer service issues by 2029, with a 30 percent cut in operational costs, is the number most vendor decks quote; it is a forecast. Third, every contact-centre incumbent now ships an agent product, so the buying decision is often "platform inside our CCaaS" against "specialist platform on a SIP trunk". Fourth, the regulator has already spoken: the FCC confirmed in February 2024 that an AI voice is an artificial voice under the TCPA. Fifth, the US has no national AI-disclosure statute for calls, but it has state laws and a federal proposal, so disclosure by default is the only sensible configuration.

Regulatory quick card

The compliance matrix row for this market is us-federal. The rule as published, in brief, and informational rather than advice:

• Consent. The FCC's declaratory ruling of 8 February 2024 (FCC 24-17) says AI-generated or cloned voices are "artificial or prerecorded" voices under the TCPA. Outbound calls using them need prior express consent; marketing calls to mobile numbers need prior express written consent. Inbound calls the consumer initiates are outside this rule.
• Calling hours. 47 CFR 64.1200(c)(1) permits telephone solicitations only between 8 a.m. and 9 p.m. in the called party's local time.
• Identification. Artificial-voice calls must state the business name at the start and give a callback number (64.1200(b)).
• Recording. Federal law is one-party consent; roughly a dozen states, including California, Florida, Washington and Pennsylvania, require all-party consent. Announce recording at the start unless counsel says otherwise.
• AI disclosure. No federal statute yet; several states have bot-disclosure laws and the FCC proposed an explicit disclosure duty in 2024. Disclose by default.
• Sector overlays. HIPAA makes the agent vendor a business associate when it hears patient information. Regulation F (12 CFR 1006.14) presumes a violation above seven call attempts per debt in seven days, and within seven days after a conversation. GLBA's Safeguards Rule covers customer financial information.

Telephony and numbering

Calls reach an agent over the PSTN through a carrier, a CPaaS provider or the telephony bundled into a CCaaS platform. Numbers are ten-digit North American Numbering Plan numbers; toll-free 8xx ranges are common for inbound, and local numbers are bought for local presence on outbound. The hand-off into the agent is usually a SIP trunk or SIP forwarding from an existing phone system.

The part buyers underestimate is call authentication. Under STIR/SHAKEN, the provider that puts a call onto the IP network signs it with an attestation: A when it knows the caller and the caller's right to the number, B when it knows the caller but not the number, C when it knows neither. All US voice service providers must have a current certification in the FCC's Robocall Mitigation Database, and terminating carriers must block traffic from providers that are not listed; annual recertification started with a 1 March 2026 deadline (reported). In May 2026 the FCC proposed codifying the attestation criteria and tightening know-your-upstream-provider duties (reported, not yet final). For a buyer this translates to one question: who signs our calls, and at what level? A new number pulled from a shared CPaaS pool and signed at B or C is how a legitimate reminder campaign ends up labelled "Spam Likely". Registering numbers to your business with the analytics providers and holding numbers steady matters as much as the agent's script.

Language and accent gates

English dominates, but a US agent fails on things that have little to do with vocabulary: telephone-band audio, speakers talking over hold music, fast digit strings for phone numbers and dates of birth, street names and surnames, and ZIP codes that a formatting layer mistakes for dates. Spanish is the second language buyers ask for most. Test a Spanish-first greeting path and a caller who switches between Spanish and English inside one sentence, not a translated menu. Bring your own recorded callers from your own region; a vendor's demo audio will not contain your accents.

Data residency and hosting

There is no federal rule that customer audio or transcripts stay in the United States. HIPAA and GLBA regulate safeguards and contracts, not geography, and state privacy statutes such as California's add notice and deletion duties. In practice most regulated buyers specify US hosting anyway, and the harder requirement is the sub-processor list: the agent platform, the telephony provider, the speech recogniser, the language model and the voice synthesiser are often five companies. Ask for the list, the retention period for recordings and transcripts, and a no-training clause on your audio. If any of those five cannot be named, the data map is incomplete.

Buyer landscape

Small businesses buy a monthly subscription that answers the phone and books into their software; the decision is made by an owner or office manager in a week. Mid-market and enterprise buyers run a procurement with security review, a telephony integration and a compliance sign-off; the decision takes a quarter. The five industries listed above lead for structural reasons: dental and medical practices lose bookings at peak hours, contractors lose calls to the weather, collectors live under Regulation F attempt caps, insurers record every claims call, and dealer groups buy through their CRM and dealer-management vendors. Each use-case page under those industries carries the US compliance notes.

Vendor landscape

The vendor list in this page's data is alphabetical and typed, not ranked. Global platforms sell an agent builder with the voice stack included or pluggable. CCaaS incumbents sell the agent as a feature of the contact centre you may already run, which simplifies telephony and reporting and limits your choice of components. Infrastructure vendors sell telephony, numbers or speech components that platforms build on; they appear here because the STIR/SHAKEN and numbering questions above are answered by them, not by the agent builder. Any of the twenty-one names can pass or fail your demo. The protocol is in the demo guide; the acceptance test is a booking or a payment arrangement landing in your own system during the call.

Questions to ask vendors in this market

The six questions in this page's data, in the order a weak answer should end the conversation: who signs your calls and at what attestation; how consent is proven before each dial; how the calling window is enforced when area code and time zone disagree; what the agent says to a California number in the first turn; whether a HIPAA or GLBA-grade agreement with a full sub-processor list will be signed; and the all-in cost per connected minute at double your volume.