What Call Center is
Call Center is a phone agent. Customers call your workspace's number, and the AI agent you built in the Agents app answers live — listening and replying as the caller speaks, on OpenAI Realtime, in the voice, language and pace you chose. It is the same agent that answers on WhatsApp and the website, so its business details, FAQ, rules, tone, greeting and hand-off line carry over, trimmed for speech. Every call is logged with its transcript.
What you set up
- Choose which of your agents answers, and connect a phone number to it.
- Choose its voice (10 to pick from, each playable with one click), the language it answers in, and its speaking speed.
- Rehearse with a live test call from your browser — speak, or type what the caller says — before you point the number at it.
- Read every call afterwards, line by line, in the call log.
- Have it hand over properly: the agent’s escalation rule — when to bring in a person, and the line to say — is part of every call.
- Send callers to WhatsApp for anything that needs a link or a long answer — the agent never reads web addresses aloud and offers to follow up there.
Every call is saved as a transcript: who said what, and when.
Before you start
- An agent with something to say. Call Center adds nothing to what the agent knows. An empty agent will be an empty voice. Fill in the FAQ, business details and rules first — see the Agents app guide.
- Access to Call Center. It is switched on per account. If you sign in and land on a "request access" page, send the request there.
- A browser with a microphone. Test calls run in your browser. If the mic is blocked you can still type your side of the call.
What the agent says on the phone: a call is built from the same agent, trimmed for speech — its tone, greeting, business details and hours, the first 30 FAQ items, your active rules, your additional instructions and its hand-off rule. It does not read the catalog or the links list to callers, and it never reads out a web address — if someone asks for a link it offers to follow up on WhatsApp.
Pick the agent
One agent answers per workspace. It is the same agent that answers on WhatsApp and the website, so what you teach it once, it says everywhere.
Connecting the agent and the number is done in the app (switch to “In the app” above). Before you do, have Claude check the agent you are about to connect.
Claude reads the agent with get_agent_config and answers from what is really saved. A gap it names ("no opening hours") is a gap a caller will hit.
- Open Call Center and click Settings at the top.
- Under Agent on the phone, open Choose an agent… and pick one. A “live” tag marks agents already live.
- Click Connect. The card now reads “<name> answers your calls”.
No agent in the list? The card says so and offers "Build an agent" — that opens the Agents app.
Connect a phone number
The number is how customers reach the agent: they call it, the agent picks up. Connect it once you have rehearsed with a test call.
Do this in the app.
- Open Settings in Call Center.
- Choose Connect a phone number and pick the number that should reach your agent.
- Call the number yourself and confirm the agent answers in the voice you chose. The call appears in Calls, with its transcript.
Voice, language and speed
Callers hear the voice before they hear a single word of content. Choose it by ear, not by name.
Pick the voice, language and speed in the app. With Claude, tune how the agent talks — its tone and how long its answers run. A phone answer should be short.
Claude uses set_agent_persona. Note it is the same persona the agent uses on WhatsApp and everywhere else, so the change applies there too.
- In Settings, open Voice, language & speed in the side menu.
- Under Call language, leave “Same as the agent” or pick a language. If a caller speaks another language the agent switches to theirs.
- Under Voice, click a voice to hear a short clip of it. Marin and Cedar are tagged “Most natural”.
- Under Speaking speed, drag the slider (0.75× to 1.5×). Slightly slower is easier to follow on a phone line. Let go and it plays the voice at that speed.
Voice clips cost nothing: the clips are pre-recorded, so click as many voices as you like. Only a test call uses your minutes.
Make a test call
The test call is the real thing in your browser: the agent answers live, in the voice, language and speed you set. It is the only way to know how it sounds.
Place the test call in the app. With Claude, get the script: the questions real customers actually ask, so you test what matters and not just “hello”.
Claude reads list_conversations and get_conversation and hands back your own customers’ questions. Open the test panel in the app (next tab) and ask them one by one.
- Click Test call in the top bar, or Hear it in a test call on the Voice page. A panel opens beside the page.
- Click the green Start test call button and allow the microphone. The agent greets you first.
- Ask your questions out loud — or type them in Type what the caller says…. A countdown shows the time left.
- Click End call (or let it finish). The call is saved, with a View call link.
Read the call log
Every call is saved with its transcript, so you can read what the agent actually promised. This is where you find the answers that need fixing.
Open a call in the app and copy its transcript, then paste it to Claude to review.
- Click Calls in the top bar. Three numbers sit on top: how many calls, average length, last call.
- Use the chips — All, Phone, Test — to filter. Test shows the calls you placed from the app; Phone shows calls that came in on your number.
- Click a row to open the call: who, when, how long, the voice and speed, then the Transcript, line by line with timestamps.
Improve the agent from what callers asked
Call Center does not teach the agent — the Agents app does. So the loop is: call, read the transcript, fix the answer where the agent keeps its knowledge, call again.
This is where Claude earns its place. Paste what went wrong and ask for the fix — it edits the FAQ, your rules or the additional instructions, which are exactly what the phone prompt reads.
Behind the scenes Claude reads with get_agent_module and writes with patch_agent_module (FAQ, business, guidelines) or set_extra_instructions. These change a live agent — which is why the prompt asks to see the change first. Then place the test call again.
- In Settings click Open in Agents on the connected-agent card. The agent opens in the Agents app.
- Fix the answer where it lives: a question in the FAQ, a line in the business details, or a rule in Guidelines.
- Come back to Call Center and click Call again in the test panel.
Not sure where the agent keeps something? See the Agents app guide.
Hand-off and WhatsApp follow-up
Two things make a voice agent feel finished: it knows when to hand a caller to a person, and it does not stall on things you cannot say out loud.
- Hand-off. The agent’s escalation rule (when, and the line to say) is read into every call. It says the line you set.
- WhatsApp follow-up. Asked for a link, a website or a long detail, it says to message you on WhatsApp after the call and it will send it there. Connect your agent to WhatsApp so the follow-up arrives.
Claude uses get_agent_config to read the current additional instructions, then set_extra_instructions, which replaces the whole overlay, so it must keep what is there. Edit the structured hand-off rule itself in the Agents app.
- In Settings click Open in Agents on the connected-agent card.
- Set the hand-off rule: when the agent should pass a customer to a person, and what it says. Connect WhatsApp under channels so the follow-up lands there.
- Return and test: ask for a person in a test call and listen for the line.
Minute limits
Voice runs on a live voice engine that is billed by the minute, so every account has a voice-minute allowance. By default it is 600 seconds — 10 minutes — in total per user. Test calls draw from it.
- A single test call never runs past 30 seconds — and ends sooner if your remaining minutes are lower.
- When your voice minutes run out, the test panel says “You have used all your voice minutes. Ask us to raise the limit.”
- Need more minutes? The limit is set per user — ask us and name the account.
Spend minutes on the questions that matter: listen to voices in the free clips, then spend test calls on the real questions, not on "can you hear me".
Your first week
- Day 1: fill in the agent’s FAQ, hours and rules; connect it in Call Center.
- Day 2: pick a voice by ear, and set the speed a notch slower than normal.
- Day 3: place three test calls with the questions your customers really ask.
- Day 4: read the transcripts; list every answer you would not give.
- Day 5: fix them in the Agents app (or with Claude) and call again.
- Then: let someone who does not know the business make a call and tell you what felt off.
Common mistakes
- Pointing the number before you rehearse. Make three test calls first, so the first real caller meets an agent you have already heard.
- Connecting an empty agent. The voice only says what the agent knows.
- Keeping catalog answers in the catalog only. The phone prompt does not read the catalog. Put prices callers will ask about in the FAQ.
- Expecting it to read a link. It never says a web address aloud; it offers to follow up on WhatsApp instead.
- Judging it from the voice clips. The clips show the voice. Only a test call shows the agent.
- Setting the voice in the wrong place. Voice, language and speed live in Call Center settings; how the agent talks lives in its persona.