Voice Agent Platforms

Retell AI vs Ultravox: priced, tested on real calls, and which to pick

Pricing and features, side by side. Last verified October 24, 2026. Spot a wrong price? support@cozzo.io

Cozzo’s tip: start with the billing row. It’s where the surprises hide.

Cozzo’s verdict. Short answer: Ultravox is the cheaper, simpler bill, and Retell AI is the easier one to scale and to use with patient data. Ultravox charges a flat $0.05 a minute with its speech-native model and voices included, but Pay as you go stops at 5 calls at once and a HIPAA BAA needs an Enterprise plan. Retell costs $0.07–$0.31 a minute depending on the voice and model you pick, includes 20 calls at once, and lets you self-sign a BAA at no extra fee. On our own phone calls the two were close: Retell replied a little faster on Oct 20 (1.04 s vs 1.18 s median), Ultravox passed more Round 4 receptionist calls (14 of 15 vs 12 of 15), and in Round 5 Retell was cleaner on gym and after-hours calls.

5 of 8 rows differ

Retell AI and Ultravox compared: type, billing style, starting price, billing, hipaa / baa, best for, key features, last verified
Detail	Retell AI	Ultravox
TypeSame	BothVoice Agent Platforms
Billing styleSame	BothPay as you go
Starting priceDiffers	$0 platform fee; $0.07–$0.31/min for voice agents	$0.05/min (first 30 min free)
BillingDiffers	Usage-based (per minute), pay as you go	Per minute
HIPAA / BAADiffers	HIPAA compliant; self-serve BAA with no additional fee (Retell compliance docs)	Not listed
Best forDiffers	Teams that want a no-code flow builder plus an API with itemized per-minute pricing	Developers wanting a speech-native model at a flat per-minute rate
Key featuresDiffers	No-code flow builder and API Pre-built agent templates and call analytics Choice of many LLMs and voices (incl. ElevenLabs) priced per minute	30 free minutes SIP at 0.5¢/min (0.48¢ on Pro) Speech-native realtime model
Last verifiedSame	BothOctober 24, 2026

Cozzo testedVoice agent latency on real phone calls

Retell AI: 1.04 s median reply time (tied 1 of 8, 11 calls)
Ultravox: 1.18 s median reply time (3 of 8, 11 calls)

Real phone calls, vendor defaults, Oct 20, 2026. Small samples, so treat close numbers as ties. See the method and limits.

Measured on Cozzo’s test calls

Retell AI: 1.04 s median reply time (11 phone calls); cost $0.080–0.084 per ~32 s call (about $0.15/min)
Ultravox: 1.18 s median reply time (11 phone calls); cost about $0.24 in total, after the free 30 minutes ($0.05/min list price)

From our own phone calls on Oct 20, 2026, vendor defaults. Measured cost is what our calls cost, not a list price.

Cozzo-tested · Round 4 · October 22, 2026

AI receptionist test: Retell AI vs Ultravox

Calls passed out of 3 on each scenario, same dental-office prompt for both.

Retell AI · 12/15 · 1.38 s median reply

Book a new patient
Reschedule
Unknown insurance
Interruption
Dental emergency

Ultravox · 14/15 · 1.27 s median reply

Book a new patient
Reschedule
Unknown insurance
Interruption
Dental emergency

† Callback taken, but the number was read back wrong at least once. 3 calls per scenario; small samples.

See the AI receptionist benchmark →All voice AI benchmarks →

See the full head-to-head test results →

Retell AI Pricing Explained →Ultravox Pricing Explained →

Ultravox bills one rate for every minute an agent is on a call: $0.05, covering its speech-native model and built-in voices, after 30 free minutes. Pay as you go has no monthly fee and a hard cap of 5 concurrent calls; Pro is $100 a month and removes the cap. Calls over Ultravox SIP add 0.5¢ a minute (0.48¢ on Pro), and the phone number and carrier minutes come from your own carrier. Retell AI has no platform fee: a minute is built from its voice infrastructure ($0.055), a voice ($0.015 for Retell, Cartesia or OpenAI voices, up to $0.10 for ElevenLabs v3 and v4), the LLM you pick (priced per model) and telephony ($0.015 a minute on a Retell number, nothing extra on your own SIP trunk). Retell lists the total as $0.07–$0.31 a minute, with 20 concurrent calls included.

Pick Ultravox if you want the lowest, most predictable per-minute bill and you’re happy to bring your own phone carrier. One $0.05 rate covers the model and voice, and it did well on our receptionist tests: 14 of 15 Round 4 calls passed and it stopped talking fastest when interrupted (0.34–0.48 s). Watch two limits: Pay as you go handles 5 calls at once, and a BAA for patient data needs an Enterprise plan.

Pick Retell AI if you want to choose your own LLM and voice, need more than 5 calls at once without a monthly fee (20 are included), want phone numbers from the same vendor, or handle patient data and want to self-sign a BAA today. On our calls it replied slightly faster (1.04 s median on Oct 20) and passed every gym and coaching quote, booking, triage and after-hours call in Round 5, but read the callback number back correctly 0 of 3 times in Round 4 (1 unclear).

Sources: Retell AI · Ultravox

Retell AI vs Ultravox: prices and plans

	Retell AI	Ultravox
How you pay	Pay as you go, $0.07–$0.31/min. No platform fee, minimums or contracts. Enterprise: custom pricing	$0.05/min after 30 free minutes. Pay as you go $0/month; Pro $100/month; Enterprise custom
What one minute includes	Voice infra $0.055 + voice $0.015–$0.10 + LLM by model (e.g. GPT 5.1 $0.04, GPT 4.1 mini $0.0128) + telephony	Ultravox’s speech-native model and built-in voices, in one rate. An outside voice (your own ElevenLabs or Cartesia key) is billed by that provider
Phone numbers and carrier	Retell numbers $2/mo and US calls $0.015/min (Twilio or Telnyx). No charge on your own SIP trunk or carrier	No phone numbers listed: you connect Twilio, Telnyx, Plivo, Exotel or your own SIP, and they bill you. Ultravox SIP adds 0.5¢/min (0.48¢ on Pro)
Concurrent calls	20 included, then $8 per extra call a month. Enterprise from 50+	Up to 5 on Pay as you go (hard cap). No hard cap on Pro ($100/mo). Priority concurrency on Enterprise
How calls are billed	To the nearest second, summed monthly; silence counts; after a transfer only telephony continues; failed calls aren’t charged	Rounded up to the next 6 seconds ($0.005 each); billed monthly in arrears, or early once usage passes $10 (Pay as you go) or $100 (Pro)
Free testing	Sign up free; simulation testing included	30 free call minutes, plus unlimited free playground calls in the web console
HIPAA / BAA	SOC 2 Type 1 and 2, HIPAA, GDPR. BAA self-signed online at no additional fee	BAA on an Enterprise plan (Ultravox docs); any account can delete call data through the API
Extras	Knowledge base +$0.005/min (10 free), PII removal +$0.01/min, branded calls +$0.10, SMS $0.01/message	Threads (background agents) $2 per 1M input tokens and $15 per 1M output tokens; 1 custom voice clone (5 on Pro)
1,000 call minutes a month	About $110 on your own carrier, or about $127 on a Retell number, at Retell’s default calculator mix	$50 ($55 over Ultravox SIP), plus your carrier’s number and minutes
5,000 call minutes a month	About $550 on your own carrier, or about $627 on a Retell number	$250 ($275 over Ultravox SIP), plus your carrier. Add $100 for Pro if you need more than 5 calls at once

Retell AI

How you pay: Pay as you go, $0.07–$0.31/min. No platform fee, minimums or contracts. Enterprise: custom pricing
What one minute includes: Voice infra $0.055 + voice $0.015–$0.10 + LLM by model (e.g. GPT 5.1 $0.04, GPT 4.1 mini $0.0128) + telephony
Phone numbers and carrier: Retell numbers $2/mo and US calls $0.015/min (Twilio or Telnyx). No charge on your own SIP trunk or carrier
Concurrent calls: 20 included, then $8 per extra call a month. Enterprise from 50+
How calls are billed: To the nearest second, summed monthly; silence counts; after a transfer only telephony continues; failed calls aren’t charged
Free testing: Sign up free; simulation testing included
HIPAA / BAA: SOC 2 Type 1 and 2, HIPAA, GDPR. BAA self-signed online at no additional fee
Extras: Knowledge base +$0.005/min (10 free), PII removal +$0.01/min, branded calls +$0.10, SMS $0.01/message
1,000 call minutes a month: About $110 on your own carrier, or about $127 on a Retell number, at Retell’s default calculator mix
5,000 call minutes a month: About $550 on your own carrier, or about $627 on a Retell number

Ultravox

How you pay: $0.05/min after 30 free minutes. Pay as you go $0/month; Pro $100/month; Enterprise custom
What one minute includes: Ultravox’s speech-native model and built-in voices, in one rate. An outside voice (your own ElevenLabs or Cartesia key) is billed by that provider
Phone numbers and carrier: No phone numbers listed: you connect Twilio, Telnyx, Plivo, Exotel or your own SIP, and they bill you. Ultravox SIP adds 0.5¢/min (0.48¢ on Pro)
Concurrent calls: Up to 5 on Pay as you go (hard cap). No hard cap on Pro ($100/mo). Priority concurrency on Enterprise
How calls are billed: Rounded up to the next 6 seconds ($0.005 each); billed monthly in arrears, or early once usage passes $10 (Pay as you go) or $100 (Pro)
Free testing: 30 free call minutes, plus unlimited free playground calls in the web console
HIPAA / BAA: BAA on an Enterprise plan (Ultravox docs); any account can delete call data through the API
Extras: Threads (background agents) $2 per 1M input tokens and $15 per 1M output tokens; 1 custom voice clone (5 on Pro)
1,000 call minutes a month: $50 ($55 over Ultravox SIP), plus your carrier’s number and minutes
5,000 call minutes a month: $250 ($275 over Ultravox SIP), plus your carrier. Add $100 for Pro if you need more than 5 calls at once

Prices read on retellai.com/pricing and ultravox.ai/pricing on Oct 24, 2026; billing and BAA details from docs.retellai.com and docs.ultravox.ai. Retell examples use the mix its own calculator shows ($0.055 voice infra + $0.015 voice + $0.04 LLM = $0.11/min; +$0.015/min and $2/mo for a Retell number), before add-ons. Ultravox examples leave out the one-time 30 free minutes and your carrier’s charges, which Retell’s own-carrier figures also leave out. Our own Retell test calls on default settings came to about $0.15/min.

What Cozzo measured on real calls

	Retell AI	Ultravox
Reply speed (Oct 20 phone calls)	1.04 s median, 11 calls, vendor defaults	1.18 s median, 11 calls, vendor defaults
Reply speed (browser link, no phone network)	0.76 s median	0.49 s median
Phone transcription errors (Oct 20)	0.0%	6.9%, all from the caller’s closing “Thanks, bye” being cut off as the call ended; the three test questions had no errors
Round 4 receptionist test (dental script)	12 of 15 calls passed; 1.38 s median reply; callback number read back correctly 0 of 3 times (1 unclear); stopped within 0.40–0.50 s when interrupted	14 of 15 calls passed; 1.27 s median reply; 2 of 3 new-patient bookings passed (they need a correct number read-back), and in the unknown-insurance calls it took the callback but read the number back wrong at least once; stopped within 0.34–0.48 s when interrupted
Round 5: gym	Passed every quote, booking, triage and after-hours call; stopped within 0.46 s; 1,280 ms median reply	Passed quotes, bookings and triage; failed after-hours (said the gym was open until 9 PM, then offered a 10 PM tour); stopped within 0.42 s; 1,520 ms median
Round 5: career coaching	Passed every call; stopped within 0.46 s; 1,280 ms median reply	Passed every call; stopped within 0.38 s; 1,340 ms median reply
Round 5: roofing & HVAC	Quote 0 of 2 and booking 1 of 2 (both scored with the number read-back), read-back 1 of 4; emergency and after-hours passed; 1,540 ms median	Quote, booking and read-back unresolved (its own transcript had the right number, the recording didn’t); emergency passed but also told the caller to call 911 for a roof leak; after-hours failed; 1,600 ms median
Measured cost	$0.080–$0.084 per ~32 s call (about $0.15/min) with Retell’s default voice and LLM	About $0.24 in total after the free 30 minutes (most of our Ultravox time was free)

Retell AI

Reply speed (Oct 20 phone calls): 1.04 s median, 11 calls, vendor defaults
Reply speed (browser link, no phone network): 0.76 s median
Phone transcription errors (Oct 20): 0.0%
Round 4 receptionist test (dental script): 12 of 15 calls passed; 1.38 s median reply; callback number read back correctly 0 of 3 times (1 unclear); stopped within 0.40–0.50 s when interrupted
Round 5: gym: Passed every quote, booking, triage and after-hours call; stopped within 0.46 s; 1,280 ms median reply
Round 5: career coaching: Passed every call; stopped within 0.46 s; 1,280 ms median reply
Round 5: roofing & HVAC: Quote 0 of 2 and booking 1 of 2 (both scored with the number read-back), read-back 1 of 4; emergency and after-hours passed; 1,540 ms median
Measured cost: $0.080–$0.084 per ~32 s call (about $0.15/min) with Retell’s default voice and LLM

Ultravox

Reply speed (Oct 20 phone calls): 1.18 s median, 11 calls, vendor defaults
Reply speed (browser link, no phone network): 0.49 s median
Phone transcription errors (Oct 20): 6.9%, all from the caller’s closing “Thanks, bye” being cut off as the call ended; the three test questions had no errors
Round 4 receptionist test (dental script): 14 of 15 calls passed; 1.27 s median reply; 2 of 3 new-patient bookings passed (they need a correct number read-back), and in the unknown-insurance calls it took the callback but read the number back wrong at least once; stopped within 0.34–0.48 s when interrupted
Round 5: gym: Passed quotes, bookings and triage; failed after-hours (said the gym was open until 9 PM, then offered a 10 PM tour); stopped within 0.42 s; 1,520 ms median
Round 5: career coaching: Passed every call; stopped within 0.38 s; 1,340 ms median reply
Round 5: roofing & HVAC: Quote, booking and read-back unresolved (its own transcript had the right number, the recording didn’t); emergency passed but also told the caller to call 911 for a roof leak; after-hours failed; 1,600 ms median
Measured cost: About $0.24 in total after the free 30 minutes (most of our Ultravox time was free)

Small samples (1–3 calls per scenario per vendor in Rounds 4 and 5, 11 calls each on Oct 20), so treat close numbers as ties. Each vendor ran on its default model and voice. Full method and limits are on each benchmark page.

Questions

Is Ultravox cheaper than Retell AI?

On list price, usually yes. Ultravox is $0.05 a minute with the model and voice included, so 1,000 call minutes a month is $50 ($55 over Ultravox SIP) plus your carrier. At Retell’s default calculator mix ($0.11 a minute) the same 1,000 minutes is about $110 on your own carrier. Retell can get closer with a cheaper LLM and voice (it lists $0.07 a minute at the low end), and Ultravox adds $100 a month if you need Pro for more than 5 calls at once.

Which is faster, Retell or Ultravox?

It’s close. On Cozzo’s Oct 20 phone calls Retell AI’s median reply was 1.04 s and Ultravox’s 1.18 s. In our Round 4 receptionist calls Ultravox was quicker (1.27 s vs 1.38 s), and in Round 5 Retell was quicker on gym, coaching and roofing calls. On a browser connection with no phone network, Ultravox was faster (0.49 s vs 0.76 s).

Which handled receptionist calls better in Cozzo’s tests?

In Round 4 (a dental script) Ultravox passed 14 of 15 calls and Retell 12 of 15; Retell’s misses were callback numbers read back wrong. In Round 5 Retell passed every gym and coaching call, while Ultravox failed the after-hours call in both the gym and roofing tests (it passed the coaching one). Both had trouble with callback numbers on roofing calls, so test your own script before you go live.

Do Retell AI and Ultravox support HIPAA?

Retell says it’s HIPAA compliant and SOC 2 Type 1 and 2 certified, and you can self-sign its BAA online at no additional fee. Ultravox’s docs say it signs BAAs for customers with HIPAA needs on an Enterprise plan, and suggest building with non-patient data first.

How many calls can each handle at once?

Retell includes 20 concurrent calls on pay as you go, then charges $8 a month for each extra one. Ultravox’s Pay as you go has a hard cap of 5; its $100-a-month Pro plan removes the hard cap, and Enterprise adds priority concurrency.

Do I need my own phone number with Ultravox?

Yes. Ultravox’s pricing page lists no phone numbers, so you connect a carrier such as Twilio, Telnyx, Plivo or Exotel, or your own SIP system, and that carrier bills you. Retell can sell you a number ($2 a month, US calls $0.015 a minute) or use your own at no extra charge.

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