Inbound calls
Answer questions and capture the details your team needs.
Voice agents for
real conversations
Build, deploy, and monitor AI agents that answer calls, qualify leads, and work with your business tools. All from one platform.
Conversation previewInbound
AGENT
Thanks for calling. How can I help you today?
CALLER
I need to book a service visit for tomorrow.
AGENT
Of course. Let me check what’s available.
↳ check_availability
Everything you need for better conversations
Design the conversation
Build your call flow visually. Give your agent instructions, tools, and a clear path to the next step.
Connect your stack
Choose your voice and model. Bring your phone numbers and connect the systems your team already uses.
Learn from every call
Review transcripts, extract the details that matter, and evaluate conversations against your own criteria.
Design the conversation
Build your call flow visually. Give your agent instructions, tools, and a clear path to the next step.
Incoming call
Front desk agent
Understand intent · collect details
Take action
Call your tools
Transfer call
Bring in your team
Connect your stack
Choose your voice and model. Bring your phone numbers and connect the systems your team already uses.
✳ Winter
Language model
OpenAIAzure OpenAI
Speech & voice
DeepgramElevenLabs
Telephony
TwilioTelnyx
Learn from every call
Review transcripts, extract the details that matter, and evaluate conversations against your own criteria.
Service enquiryCompleted
Call outcomeAppointment requested
ServiceHeating repair
LocationSan Francisco
Next actionSend to dispatch
Summary sent to your workflow
A first conversation.
At every opportunity.
Follow up with new leads, confirm appointments, and reach your customers. Build your campaign once, then manage calls, retries, and outcomes from one place.
Appointment reminders Running
Contacts128
Completed96
Confirmed82
ContactOutcomeDuration
Alex MorganConfirmed1:42
Jordan LeeConfirmed2:08
Sam TaylorTransferred3:16
Casey DavisRetry scheduled—
Retry rules enabled Illustrative campaign
Built to work
with your team.
Give your agent a clear job and the tools to do it. Define when to take action, when to ask another question, and when to connect the caller to a person.
Winter agent
Your team
“Alex needs help scheduling a heating repair. They’re available tomorrow morning.”
The building blocks
for better calls.
From a single phone number to your entire call operation. Everything you need to build, connect, and improve your voice agents.
Outbound campaigns
Reach contacts with scheduled calls and automatic retries.
Human handoffs
Route the conversation to a person when it needs one.
Tools & integrations
Take action during the call with HTTP and MCP tools.
Your voices & models
Build with the speech and language providers you choose.
Call intelligence
Review recordings, transcripts, and extracted outcomes.
Put the next call to work.
Frequently asked
questions
What do I need for my first call?
Create a workspace, connect your own voice and language-model providers, then create an agent and test it in your browser. You do not need a phone number for a browser test. Telephone calls and transfers need a connected carrier and number. The hosted Winter trial is available only to invited workspaces.
What can I build with Winter?
Build inbound receptionists, lead qualification agents, appointment reminders, and other phone workflows. You define the conversation, the details to collect, and the actions to take.
Can I bring my own phone numbers?
Connect a supported telephony provider such as Twilio, Telnyx, or Plivo, then route your numbers to a Winter agent.
Which voices and models can I use?
Configure your language model, speech recognition, and voice provider independently. Winter brings those choices together in one workflow.
Can an agent take action during a call?
Yes. Connect HTTP or MCP tools to look up information, update your systems, and carry out the next step during the conversation.
How do human transfers work?
Add a transfer action and destination to your phone workflow. The agent can hand off when the caller asks or when your business rules require it.
How do I review call quality?
Review recordings and transcripts, define structured fields to extract, and configure post-call evaluation criteria for your workflow.
Build your first agent
Connect your own voice and model providers, build an agent, and test it in your browser. Add a phone number when you’re ready for calls.
