How to choose an AI phone agent in 2026
Last updated: November 9, 2026. This is independent research based on vendors' published pricing and documentation, read on November 9, 2026. We did not test these products. See the ranked list.
Answer in brief
Start with your calls, not the features. Decide whether you need inbound answering, outbound dialing or both. Estimate your monthly volume, average call length and peak number of simultaneous calls. Then judge each vendor on what a caller actually hears and what you actually pay: response latency, voice quality, how it connects to your phone number, how transfers work and are billed, and whether it bills per minute, per call or per caller. If you have developers, build on a platform such as Retell AI, Vapi or Bland AI. If you want a ready-made agent, buy a receptionist such as Smith.ai, Goodcall, Rosie or Phonely.
Top pick if you are unsure: Retell AI. It's pay as you go with a $10 credit and 20 free concurrent calls, so you can prove a phone agent on real calls before you commit.
Step 1: Map your calls
- Direction: inbound only (receptionist), outbound (reminders, lead follow-up) or both.
- Volume and length: long calls favor per-call or per-caller billing, and many short calls favor per-minute billing.
- Peak concurrency: Retell includes 20 simultaneous calls, Vapi's free tier 4, Bland Start 10, and Phonely unlimited on every plan.
Step 2: Latency, the silence callers notice
Vendors publish their own speed claims. Bland AI claims under 400 ms, Retell AI about 600 ms, Vapi about 800 ms end to end typically, and Phonely 182 ms to first token for its Alma model. These figures are measured in different ways. Don't rank vendors on the claims. Place timed test calls with the exact model and voice you'll run, and remember that a bigger LLM usually means a slower reply.
Step 3: Voice quality and language
Platforms let you choose a voice: Vapi lists 15 TTS providers, and Retell offers platform voices with fallback plus ElevenLabs, Cartesia and others. Receptionists bundle voices. Rosie offers 10+ voices with English and Spanish on every call, and Phonely lists 1,000+ voices in 50+ languages, with voice cloning. Listen to your own script, read in your accents and noise conditions.
Step 4: Telephony, and keeping your number
| Connection | What it means | Examples |
|---|---|---|
| Call forwarding | Keep your carrier and forward calls to the agent | Goodcall (carrier guides), Rosie |
| Vendor numbers | Buy numbers from the vendor | Retell ($2/month), Vapi (included numbers by package), Phonely (3–5 free) |
| Bring your own SIP or carrier | Connect Twilio, Telnyx, Vonage or a PBX over SIP | Retell (no charge), Vapi, Bland AI, PolyAI (no charge), Synthflow, Phonely Enterprise |
Step 5: Transfers and what they cost
Check that warm or live transfer is on the plan you're buying. Rosie offers it from $149, and Smith.ai can hand callers to live receptionists. Then check how transfers are billed. Retell stops its AI fee after a transfer and charges only telephony. Bland charges $0.04–$0.05 per transfer minute unless you bring your own telephony. Phonely may bill $0.02/min after a transfer, except for SIP REFER transfers.
Step 6: Match the billing unit to your calls
| Billing unit | Vendors | Best when |
|---|---|---|
| Per minute | Retell AI, Vapi, Bland AI, PolyAI | Short calls, technical teams |
| Per call | Smith.ai | Long qualifying calls with human backup |
| Per unique caller | Goodcall | Repeat callers, variable call length |
| Bundle of minutes | Rosie, Phonely, My AI Front Desk | Small, steady volume |
| Annual contract | Synthflow | Enterprise rollouts |
Step 7: Compliance on the exact plan
A HIPAA BAA is often plan-specific. Vapi sells it as a $2,000/month add-on, Bland lists a BAA on Enterprise, and Phonely signs one for Enterprise customers. Get it in writing.
Step 8: Run a test-call script
- Call from a mobile phone in a noisy room and time the first reply.
- Interrupt the agent mid-sentence.
- Ask for a booking and confirm it lands on your calendar.
- Request a human and confirm the transfer.
- Check the transcript, recording and bill line items afterward.
FAQ
Should I build or buy an AI phone agent?
Build on Retell AI, Vapi or Bland AI if you have developers and need custom logic. Buy Smith.ai, Goodcall, Rosie, Phonely or My AI Front Desk if you want calls answered this week.
What latency is good enough for phone calls?
Vendors advertise anywhere from under 400 ms to about 800 ms, measured in different ways. Judge it on your own timed test calls.
Can I keep my existing phone number?
Usually. Forward it (Goodcall, Rosie) or connect your carrier over SIP (Retell AI, Vapi, Bland AI, PolyAI).
Can AI phone agents make outbound calls?
Yes. Retell AI, Vapi, Bland AI and Phonely support outbound calling, and My AI Front Desk allows 20 outbound calls a day. Check the rules on automated calls in your region.
Compare the leaders
Ranked list · Retell AI vs Vapi · Retell AI vs Bland AI · Vapi vs Bland AI · Smith.ai vs Goodcall · Alternatives to Retell AI · Alternatives to Smith.ai · Pricing comparison
Reviews: Retell AI · Smith.ai · Goodcall · Vapi · Bland AI · Rosie · My AI Front Desk · Phonely · Synthflow · PolyAI · Slang.ai
Official sites: · · · · · · · · · ·
Choosing chat or email support AI instead? See bestaisupportagent.com and bestaicustomersupport.com.
Sources
- Retell AI pricing
- Retell AI home page
- Vapi pricing
- Vapi FAQ
- Vapi voice providers
- Bland AI pricing
- Bland AI docs index
- Smith.ai pricing
- Goodcall pricing
- Goodcall FAQ
- Rosie pricing
- Phonely pricing
- My AI Front Desk pricing
- Synthflow pricing
- PolyAI pricing
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