Voice Agents
How Spara's AI Voice agents handle phone calls to engage, qualify, and convert leads.
The Voice agent conducts real-time AI phone conversations with leads — handling incoming sales calls and making outgoing follow-up calls. Voice agents engage leads immediately, 24/7, without requiring a human rep on every call.
Spara also offers two specialized voice-powered agent types for specific use cases:
Product Demo — Delivers live, interactive product demos over voice with synchronized visuals.
Copilot — Joins your sales meetings as a silent AI assistant that answers technical questions on demand.
This page covers standard Voice agents. See the linked pages above for the specialized types.
Use cases
Outgoing follow-up calls
Spara can call leads automatically when they complete — or fail to complete — a key action. A common example: a lead submits a marketing form but never schedules a meeting. Spara calls immediately to move them through the next step while interest is high.
Outgoing calls are triggered through Workflows using the Call Phone Step.
Incoming calls
Spara handles incoming sales calls end-to-end — answering questions, qualifying leads, and booking meetings. When a lead calls your assigned phone number, the Voice agent answers immediately, identifies the caller if possible, and conducts the conversation using the lead's available context (fields, conversation history, and CRM data).
Callback on outgoing numbers
All outgoing phone numbers automatically accept incoming calls. If a lead misses your outgoing call and calls the number back, the same Voice agent that was dispatched picks up and continues the conversation with the lead's full context intact. No additional configuration is required — this behavior is enabled by default on all outgoing numbers.
Phone number management
Phone numbers are managed centrally in your organization's settings and then assigned to individual agents or workflows.
Adding phone numbers
Navigate to Settings > Voice > Configuration to view and manage your account's phone numbers. From here you can register new numbers that become available across your account for use with Voice agents, Text agents, and Workflows.
Each phone number can serve as:
An incoming number for a Voice agent — Assign it on the agent's Configuration tab. Leads who call that number reach this agent.
An incoming number for a Text agent — Assign it on the text agent's Configuration tab.
An outgoing number for Workflows — Select it in a Call Phone or Send Text step.
Phone number ownership
Phone numbers used by Spara are hosted in Spara's telephony account. There are two common ways to get a number live:
Spara provisions a new number for you. The most common path. Spara registers a fresh number in the country and area code you choose.
You port an existing number into Spara. If you already own a phone number and want to keep it, you can transfer it into Spara's telephony account. Spara coordinates the port with your current provider.
Bring-your-own-number (where you retain ownership of the number and Spara routes calls from your carrier directly) is on the Spara roadmap but is not currently under development. Today, the number must live in Spara's telephony account.
Connecting your phone numbers to Spara
If you want a phone number you already publish on your website or marketing materials to reach a Spara Voice agent, there are two ways to wire it up.
Option 1 — Forward calls to a Spara-provided number.
The simplest path. Configure your existing phone system to forward incoming calls to a number Spara has provisioned for you. From your customers' perspective they dial the same number they always have; behind the scenes the call forwards to Spara and the Voice agent picks up.
This works with any phone system that supports call forwarding to an external number. No technical integration required — your Spara representative can help you set this up.
Option 2 — Route calls directly to Spara over SIP.
If your phone system supports SIP (Session Initiation Protocol) — common in business telephony platforms like Genesys, RingCentral, and similar — you can route incoming calls straight to Spara's SIP endpoint, skipping the intermediate forward.
This option is more efficient (one less hop) but requires technical coordination. Spara needs to share its SIP endpoint with your telephony team and allow-list your routing IPs. Expect a brief technical setup session between your team and Spara to get this working.
Most customers use Option 1 because it requires no engineering effort. Choose Option 2 when your telephony stack already speaks SIP and you want a tighter integration.
Assigning numbers to agents
Each voice agent can be assigned a phone number on the Configuration tab. This is the number the agent answers incoming calls on and uses as the caller ID for outgoing calls. Each phone number can only be assigned to one published voice agent at a time.
You can run multiple voice agents on separate phone numbers — for example, one number for sales inquiries and another for support routing. Each agent operates independently with its own instructions, abilities, and phone number.
Spara does not make cold or unsolicited outgoing calls to leads outside of your Workflows.
Branded caller ID for outgoing calls
Branded caller ID displays your business name (instead of just a phone number) on the lead's screen when an outgoing call rings, which significantly improves answer rates. It also affects whether carriers flag your calls as legitimate vs. "Spam Likely." Spara handles the registration with the telephony network on your behalf, but it requires information from you (business name, use case, sample call scripts) and typically takes several days to complete.
If you plan to use a Voice agent for outgoing calls, ask your Spara account team to kick off branded-calling onboarding as early as possible. Calls placed before registration completes may show as "Spam Likely" on the recipient's phone, which materially hurts answer rates.
Abilities
Abilities are capabilities the agent can use during a live call. They are configured on the Abilities tab of the Voice Agent Editor.
Book meeting
The agent checks your calendar, reads available slots aloud, and books the meeting through conversation
Transfer
Cold or warm transfer to a rep or team when the lead is qualified and ready to speak with someone
API request
Call an external API endpoint during a call — for order lookups, inventory checks, or internal data
Book meeting
Voice agents book meetings through conversation — not by showing a calendar widget. The flow works like this:
The agent asks the lead when they're available and checks your calendar for open slots
The agent reads the available times aloud (e.g., "I have Tuesday at 2pm or Wednesday at 10am")
The lead picks a time
The agent confirms the details (name, email) and books the meeting
The agent can filter slots by time of day based on the lead's preferences (morning vs. afternoon, weekdays only, etc.).
Booking requires a Calendar Integration connection. Spara supports Cal.com, Calendly, and others.
When you create a new voice agent, Spara automatically creates a Calendly calendar integration for it. You can change the calendar provider or customize the integration on the Abilities tab.
Transfer
Voice agents can transfer calls to a rep or team when the moment is right — for example, when a lead is qualified and ready to speak with sales.
Cold vs warm transfer
Cold transfer — The agent says goodbye and forwards the call. The lead hears ringing and connects with the rep (or voicemail). If nobody picks up, the call ends. Use this for general routing where the receiving team is reliably staffed.
Warm transfer — The agent connects your rep first, briefs them on the conversation, then drops off. The lead stays on the line throughout. If nobody picks up the warm transfer, the Voice agent stays on the call with the lead — it can continue answering questions, capture follow-up details, or end gracefully rather than dropping the caller. Use this for high-value leads where a missed handoff would be costly.
Spara recommends warm transfers by default. The recovery behavior — agent stays on if the handoff misses — keeps the lead engaged even when your rep is unavailable.
Transfer destination types
You can configure multiple named destinations (e.g., "Sales", "Support", a specific rep) on the Abilities tab. The agent chooses the right destination based on the conversation and your instructions. Each destination can be one of two types:
A phone number — A standard phone number, whether a rep's cell phone, a desk line, or a routing number at another service. Phone-number transfers work out of the box; no extra setup needed.
A SIP endpoint — A SIP address belonging to another voice system (such as your support center's SIP-based platform). SIP transfers require a brief technical setup session between Spara and the receiving system so they accept calls from us. Use this only when your downstream system explicitly requires it.
If you're unsure which type a destination is, ask the team running that destination "is this a phone number or a SIP endpoint?" — the answer determines whether the setup is plug-and-play or requires a coordination call.
API request
Voice agents can make HTTP requests to external services during a call — for example, to look up a lead's account status or pull pricing details for the service they're asking about. You configure the URL, HTTP method, any required headers, query parameters, and a request body ahead of time. The agent triggers the request at the right moment in the conversation and reads the response.
Configuration
Voice agents are configured through the Agent Editor — the same split-screen interface used for Chat, Email, and Text agents. The Instructions tab defines the agent's persona, tone, and how it handles common scenarios. The Configuration tab covers phone number assignment, voice selection, and call behavior.
For a step-by-step walkthrough, see Setting Up Voice Agents.
Voice and call settings
Voice provider — Choose from supported text-to-speech providers, including ElevenLabs. Each provider offers a different range of voices and characteristics.
Voice — Pick a voice that matches your brand. Depending on the provider, you can fine-tune characteristics like speed, stability, and similarity to control how natural and consistent the agent sounds. Customers often try a handful of voices on test calls before settling on one — the right voice has a noticeable impact on perceived quality.
Voicemail — Enable the agent to leave a scripted voicemail when a lead doesn't answer an outgoing call.
Interruption handling — Control whether the lead can interrupt the agent mid-sentence, and how sensitive the detection is. More sensitive settings feel more conversational but can cause the agent to stop talking when the lead is just acknowledging ("uh-huh"). Less sensitive settings feel more steady but can sound robotic.
Re-engagement — When enabled, the agent speaks again if the lead goes silent, keeping the conversation moving. Useful for keeping momentum on calls where the lead is distracted.
Max call duration — Optionally set a time limit for calls. If a limit is set, the agent wraps up gracefully as the limit approaches, then the call ends. If you leave this unset, calls run as long as the conversation does.
Privacy warning
Configure a custom call recording or privacy disclosure that plays at the start of each call before the agent begins its conversation. You can customize the warning text to meet local compliance requirements, and select a specific voice for the disclosure that's different from the agent's main voice.
For outgoing calls, you can also embed the disclosure directly in the agent's instructions instead of using this toggle. See How do I handle the recording disclosure on outgoing calls? for both options.
Pronunciations
On the Voice > Configuration tab, you can add custom pronunciations that apply to all Voice agents in your account. Each entry maps a word to how it should be spoken — for example, "SQL" → "S.Q.L." or your company name to its correct pronunciation.
Publishing and version history
When you publish a voice agent, the current draft becomes the live version. Spara tracks every published version in the agent's version history, so you can see what changed and when. This is useful for auditing prompt changes, rolling back if something breaks, and coordinating updates across your team.
See Saving & Publishing for details on the draft/publish workflow.
Do Not Call
Spara automatically prevents outgoing calls to leads who have opted out. When a lead requests not to be called during a voice conversation, the Voice agent records this preference. Once marked as Do Not Call, no outgoing calls will be placed to their number — including calls triggered by Workflows. Call Phone steps in a workflow are skipped for opted-out leads, and the workflow continues to the next step.
Leads with an active Do Not Call preference are marked with a visible badge on the Leads page, so your team can see at a glance which leads have opted out.
Voice events in webhooks
When a voice call ends, Spara emits a lead.updated webhook with source: "voice". Voice calls appear in a calls array on the payload — one entry per call — with start/end timestamps, whether it was incoming or outgoing, the Voice agent that handled the call, a short summary, and the transcript. See https://docs.spara.com/developers/spara-api/webhooks for the full webhook payload spec.
A/B testing
A/B testing for Voice agents is coming in June 2026. You'll be able to run two variants of a Voice agent — different prompts, voices, or abilities — in parallel and compare outcomes. Reach out to your Spara account team if you'd like to be among the first to use it.
Ask Spara AI
The Ask Spara AI tab in the Voice Agent Editor lets you chat with an AI assistant about your agent's behavior. Use it to debug why your agent said something unexpected, understand how your instructions are being interpreted, or get suggestions for improving your prompt. This is the fastest way to diagnose issues without re-reading your full instruction set.
Testing
Click Test in the agent editor to start a test web call directly in your browser. This lets you have a live conversation with your agent to verify it sounds right.
You can also test outbound calls from the voice testing dashboard. This sends a real outbound call to a phone number you specify, letting you experience the call exactly as a lead would — including caller ID, voicemail behavior, and the full call flow.
Test calls use the draft version of your agent — any unpublished changes will be reflected. This means you can iterate on your prompt and abilities without affecting live calls. Test calls are recorded and appear in the agent's call history for review.
See Testing for more details.
FAQ
How does calendar booking work on voice calls?
The agent reads available slots aloud and books the meeting through conversation. It does not show a calendar widget — the entire flow is verbal. When you create a new voice agent, a Calendly integration is automatically set up. You can change the provider or customize it on the Abilities tab. See Book meeting above for details.
How do transfers work?
Configure one or more named destinations (e.g., "Sales", "Support") on the Abilities tab. Cold transfer forwards the call directly; warm transfer brings your rep onto the line first, where the agent gives them a short verbal summary of the conversation before dropping off. The agent picks the destination based on your instructions and the conversation. See Transfer above.
Can I have multiple voice agents on different phone numbers?
Yes. Register multiple phone numbers in Settings > Voice > Configuration, then assign each number to a different voice agent on its Configuration tab. For example, you could run a sales qualification agent on one number and a support routing agent on another. Each phone number can only be assigned to one published voice agent at a time.
Can I A/B test two voice agents in parallel?
A/B testing for Voice agents is coming in June 2026. See A/B testing.
Can Voice agents leave voicemails?
Yes. If a lead doesn't answer an outgoing call, the Voice agent can leave a voicemail using a script you configure in the agent's settings under Voice and call settings.
What happens if a lead calls back an outgoing number?
The same Voice agent that placed the outgoing call automatically answers. The agent has the lead's full context from the original call attempt, so the conversation picks up naturally.
Where do I see call outcomes?
Call results appear on the lead's timeline in Leads — including whether the call was answered, transferred, or resulted in a booked meeting. You can use these outcomes as Workflows triggers and conditions.
Does the Voice agent know about the lead before the call?
Yes. If the lead has existing fields — from a CRM sync, prior chat conversation, or previous calls — the Voice agent has access to that context. This includes data from Salesforce and Hubspot (CRM) integrations.
Are voice calls recorded?
Yes. All voice calls are recorded and transcribed. You can play back recordings and review transcripts from the lead's timeline on the Leads page. The privacy warning plays at the start of the recording — see Privacy warning to customize it.
How do I set up the privacy warning?
Go to the agent's Configuration tab and find the privacy warning section under Voice and call settings. Enter your custom disclosure message and optionally select a different voice for the warning. The disclosure plays automatically at the start of each call before the agent begins its conversation.
How do I handle the recording disclosure on outgoing calls?
You have two options, and you can choose whichever feels more natural for your use case:
Use the privacy warning toggle. A consistent pre-recorded disclosure plays at the start of every call, regardless of direction. The advantage is consistency and a clear separation between the disclosure and the conversation — you can even use a different voice for the warning.
Embed the disclosure in your agent's instructions. Have the agent say it as part of the opening greeting — for example: "Hi, this is Jenna from Acme. Please note this call may be recorded for quality purposes. I'm calling because…" The advantage is a more conversational feel on outgoing calls, where some recipients are more likely to stay engaged when the disclosure flows naturally with the greeting rather than playing as a separate prompt.
Both approaches satisfy the compliance requirement that the disclosure be delivered at the start of the call. Pick the one that fits your brand — and whichever you choose, make sure every recorded call includes the disclosure in some form.
What happens when the call hits the time limit?
If you've set a max call duration, the agent wraps up gracefully as the limit approaches and the call ends when it hits. You can also leave the limit unset, in which case calls run as long as the conversation does. See Max call duration under Voice and call settings.
What happens for incoming calls outside business hours?
Spara doesn't currently offer a platform-wide business hours setting, but the agent can behave differently depending on the time of day. For example, if a lead calls outside your hours, you can instruct the agent to skip the live transfer and instead book a meeting with a rep through the calendar. The agent has access to the current time and timezone and can branch on it.
Can voice agents send SMS or text messages?
Voice agents do not send SMS directly. To follow up by text, use a workflow with a Send Text step. Outgoing SMS requires Twilio A2P registration; your Spara account team can guide you through the registration process.
Will Spara reuse the same lead record when the same phone number calls back?
Yes. Spara associates calls from the same phone number with the same lead, so conversation history, captured fields, and CRM context carry across repeat calls instead of creating duplicates.
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