AI agent voice calling connects software to a real phone conversation. A complete system needs a number, call routing, speech understanding, response generation, speech output and a way to confirm any business action. In AgentLine, hosted voice handles ordinary conversation; your external agent supplies explicit lookups and tasks when a persistent integration is configured.
Start with the smallest complete call
Create an account, an agent and a number, then call your own phone with a short approved prompt. The REST walkthrough shows the requests and transcript retrieval. If you use a connected runtime, begin with its dedicated setup guide. Number purchase and calling are paid actions; determine the test budget first.
A prompt should define the purpose of the call, the facts the assistant may use, what it must ask before acting, and what to do when it cannot help. Keep answers brief enough for a phone conversation. A per-call system_prompt replaces the saved instructions, so include the complete rules when overriding it.
Measure latency at the correct boundary
Call setup delay and conversational response latency are different measurements. Track the time from an accepted outbound request to ringing separately from the time between the caller finishing a sentence and the first audible reply. External lookups introduce another interval: request to confirmed task result.
For a useful local experiment, keep the phone, network, prompt and test utterances consistent. Record the voice preset and call IDs. Repeat ordinary questions, interruptions and lookup requests; report sample size plus median and tail delay instead of one fast example. Listen for premature replies that interrupt the caller as well as long silences. This guide publishes no measured latency advantage for AgentLine.
Choose a voice with real call tests
GET /v1/voices returns AgentLine's live catalog. Configure voice_id on an agent or override it for one outbound call. Account defaults apply only when a more specific voice is absent. The voice selection guide includes executable examples and a pronunciation test. Evaluate names, numbers, dates, interruptions and your actual language rather than relying only on a preset label.
Connect business actions explicitly
A booking request needs an authorized calendar service; a lead update needs a CRM write. A runtime or webhook service supplies confirmed facts and task results to hosted voice. When a system is unavailable, the agent should explain that the action is pending or failed. Do not turn a conversational promise into a success event without checking the destination system.
Test duplicate deliveries and retries so one call does not create two appointments or CRM activities. Keep call IDs alongside downstream record IDs. Read final transcripts for quality checks, but use the external system as the authority for whether an action happened.
Plan human escalation
AgentLine's live handoff routes to the configured owner_phone. Read the owner-transfer guide before promising a broader routing flow. If you need a warm briefing, evaluate a dedicated transfer feature and test what happens when the recipient does not answer.
Compare platforms and cost
The AgentLine, Retell, Vapi and Bland comparison links to current provider documentation. Retell's transfer options are relevant when a human handoff is central; Vapi's voice configuration is relevant when provider selection matters. For lower-level telephony choices, see AgentLine vs Twilio vs Vapi.
AgentLine's published rates are monthly plans from $20 with included US or Canada numbers, call minutes and SMS; beyond the plan, $3.00/month per number, $0.12/minute for calls (per-second after a one-minute minimum; zero-second calls are free), and $0.02 per SMS in either direction. Check pricing and your account's allowances before budgeting. Runtime hosting and external integrations can add costs.
Launch criteria
Before expanding beyond test calls, verify the greeting, correct facts, interruption handling, failed lookups, final status, transcript access and confirmed task results. Use separate tests for incoming calls and outbound calls. Repeat the checks after changing a prompt, voice or integration. A successful first call is a starting point; repeatable outcomes are the evidence that the workflow is ready.