AI Phone Agents in 2026: YC Startups + Best Alternatives

If you're a startup or SMB, voice AI is finally "buyable." You can now deploy an AI agent that answers inbound calls, handles FAQs, books appointments, routes calls to the right person, and summarizes outcomes—often without hiring a receptionist or expanding a call center.

This post is a copy/paste directory of Y Combinator (YC) voice startups that can answer phone calls (or help you build phone agents), strong non-YC startups doing the same, and practical pros/cons with a buyer checklist so you can pick fast.

Disclosure / safety note: If you deploy voice AI, avoid "human-washing" (bots pretending to be human). Consider disclosing "I'm an AI assistant" early in the call. Also check call recording + consent rules and outbound calling rules (TCPA/robocalls) if you do outbound campaigns.

What counts as a "phone-answering" AI agent?

When SMBs say "answer the phone," they usually mean:

Core capabilities: - Inbound answering (first ring), natural conversation - Intent capture: "Are you calling to book, ask a question, or speak to someone?" - FAQ + business info (hours, location, pricing, policies) - Call routing / transfer (warm transfer when needed) - Appointment booking (calendar integration) or lead capture - Post-call summary + CRM notes

Nice-to-have: - SMS follow-ups - Multiple languages - Spam filtering - Voice customization / brand voice - Analytics (containment rate, bookings, missed-calls recovered)

Pricing Models Cheat Sheet

1) Per-minute (common for builder platforms) Good when you can predict volume or need developer flexibility. Watch for "stacked" costs (telephony + STT + TTS + LLM).

2) Per location (common for restaurants/hospitality) Great for SMB chains; predictable budgeting.

3) Per agent / seat More like SaaS pricing; can be predictable.

4) Per unique caller/customer Predictable for long calls, but can surprise with many one-time callers.

YC Startups That Answer the Phone (Plug-and-Play)

Phonely (YC S24) AI call centers / phone agents with workflow automation. - Best for: SMBs wanting a serious phone agent + workflow integrations - Website: https://phonely.ai

Lovage (YC W22) Virtual receptionists across phone/text/social. - Best for: Local businesses wanting multi-channel reception - Website: https://getlovage.com

Cleon (YC X25) AI voice agents for inbound and outbound; handles FAQs, booking, orders. - Best for: SMBs wanting 24/7 inbound coverage - Website: https://getcleon.ai

BrainHi (YC S18) Automated receptionist for missed calls and appointment scheduling. - Best for: SMBs where missed calls = lost bookings

YC Vertical Phone Agents

Dental: Arini AI receptionist for dental clinics.

Restaurants: Certus AI (YC X25) Replacing the restaurant phone line with Voice AI. - Website: https://www.certus-ai.com/

Hotels: Riviera (YC W25) Hotel phone receptionist, multilingual. - Website: https://www.withriviera.com

Automotive: Sandra AI, Toma (YC W24) Multilingual AI receptionist for car dealerships. - Sandra AI: https://www.sandra-ai.com - Toma: http://www.toma.com/

Healthcare: Prosper (YC S23), Novoflow (YC S25) AI phone agents for scheduling, billing, claims. - Prosper: https://www.getprosper.ai - Novoflow: https://www.novoflow.io/

YC Platforms/APIs to Build Voice Agents

Retell AI (YC W24) Platform for building/managing AI phone agents. - Website: https://retellai.com

Vapi Voice AI for developers. - Website: https://vapi.ai

Bland AI Enterprise platform for AI phone calls. - Website: https://bland.com

Vogent (YC S21) Voice agent platform with IVR detection, phone-ready LLMs. - Website: https://vogent.ai

Top Non-YC Voice Agent Startups

Goodcall AI phone agent with unique caller-based pricing. - Website: https://www.goodcall.com/

Slang AI (Restaurants) Restaurant voice AI for reservations and guest questions. - Website: https://www.slang.ai/

Enterprise Options - Synthflow: https://synthflow.ai/ - PolyAI: https://poly.ai/ - Replicant: https://www.replicant.com/ - Parloa: https://www.parloa.com/

10-Question Buyer Checklist

1. Inbound, outbound, or both?
2. What's the handoff model (warm vs cold transfer)?
3. How do you handle failures?
4. What integrations exist (Calendar, CRM, EHR)?
5. Pricing unit: minutes, callers, agents, locations?
6. SMS follow-ups supported?
7. Analytics available?
8. Disclosure and consent handling?
9. Recordings, retention, data security?
10. Testing support (simulations, accents/noise)?

7-Day Pilot Plan

Day 1: Pick one workflow (hours/FAQs + book appointment) Day 2: Write call script (greeting, intent, FAQs, booking, escalation) Day 3: Set boundaries (what agent can/cannot do) Day 4: Test 30 calls (accents, noise, angry callers, off-script) Day 5: Soft launch (after-hours or 30-50% of calls) Day 6-7: Review, iterate, improve KB

My Shortlists by Use Case

Typical SMB: Phonely, Lovage, Cleon, Goodcall Restaurants: Slang AI, Hostie, Certus AI Dental: Arini Hotels: Riviera Automotive: Sandra AI, Toma Healthcare: Prosper, Novoflow Developers/Platforms: Retell AI, Vapi, Vogent, Bland AI Enterprise: Synthflow, PolyAI, Replicant, Parloa

Voice AI is becoming the "new front desk" for startups and SMBs—especially in industries where missed calls = lost revenue.