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AI phone agents in English

English is ThunderPhone's primary language across the whole product: agents speak and understand English on calls, the dashboard ships with an English interface, and the English documentation is the governing edition of the docs. It is also the language with the deepest voice catalog on the platform.

English is one of ThunderPhone's 47 supported voice languages and an included language, so selecting English adds no language surcharge to the Spark, Bolt, or Storm engine rate.

English voice availability and pricing

The current catalog includes 46 compatible voices for English — the largest voice selection of any language on the platform. That set spans the multilingual and bilingual voices plus 12 premium English voices: Archie, Ronald, Carson, Jameson, Daniel, Skylar, Gemma, Katie, Jacqueline, Cathy, Caroline, and Jessie.

English carries no per-minute language charge, so the engine rate applies directly: Spark at 2¢, Bolt at 5¢, or Storm at 9¢ per minute, pay as you go, with no subscription. The optional premium English voices add 3¢ per minute on top of the selected engine rate. All figures are illustrative and exclude telephony and other optional charges.

With this many candidates, shortlist by previewing voices in the builder, then test the finalists against real calls. Evaluate the names, addresses, account numbers, industry terms, and regional accents your callers actually use.

English in the dashboard and documentation

English is a shipped dashboard locale and the product's default interface language. Teams configure prompts, review calls and transcripts, and manage billing in English without any setup.

ThunderPhone publishes a dedicated English documentation edition on its docs site. English is also the governing text for the documentation as a whole: localized editions in other languages are derived from it, so the English docs are always the exact-wording reference.

English and other languages in one call

An English-first agent is not limited to English. Set English as the primary language, add any of the other supported languages, and the agent switches automatically when a caller moves into a configured additional language — then back again when the caller returns to English.

The chosen voice must support every selected language. Many of the 46 English-compatible voices are multilingual, which is what makes bilingual English-plus-one-more configurations straightforward. Test realistic switch points before going live, especially names and addresses spoken across languages.

Sample English call experience

Agent starts in English: Greets the caller, identifies the business, and asks how it can help.

Caller answers in English: Asks to reschedule a delivery for later in the week.

Agent continues in English: Confirms the caller's details, checks the approved scheduling action, and offers the available windows.

Caller switches to Spanish: Asks a clarifying question about the delivery address.

Agent switches to Spanish: Confirms the address, then follows the caller back into English when they continue in English.

Agent closes in English: Repeats the confirmed delivery window and ends the call according to the business's instructions.

The switch happens inside one call, with no separate number and no phone-tree language menu.

Build and test an English agent

  1. Set English as the primary language, or keep it as the default on a new agent.
  2. Shortlist voices from the 46 compatible options and preview them in the builder.
  3. Write the operating prompt with the exact questions, tool actions, transfers, and fallback behavior you expect.
  4. Attach only approved knowledge sources and integrations.
  5. Run browser tests and simulations with the accents, vocabulary, and any additional languages your callers use.
  6. Review transcripts, pronunciation, tool actions, and escalation behavior before deployment.

Frequently asked questions

Does ThunderPhone support English voice calls?

Yes. English is ThunderPhone's primary language, with 46 compatible voices in the current catalog — the most of any of the 47 supported languages.

Does English cost extra as a language?

No. English is an included language with no language surcharge. Calls bill at the selected engine rate — Spark 2¢, Bolt 5¢, or Storm 9¢ per minute — before telephony and other optional charges.

Are premium English voices available?

Yes. The catalog currently lists 12 premium English voices — Archie, Ronald, Carson, Jameson, Daniel, Skylar, Gemma, Katie, Jacqueline, Cathy, Caroline, and Jessie — each adding 3¢ per minute.

Is the dashboard available in English?

Yes. English is a shipped dashboard locale and the product's default interface language.

Are the ThunderPhone docs available in English?

Yes. ThunderPhone publishes a dedicated English documentation edition, and English is the governing text from which the localized editions are derived.

Can an English agent switch to another language during a call?

Yes. Add any supported language as an additional language and choose a voice that supports the full set. The agent switches automatically when the caller changes language mid-call.