What an AI voice agent needs from a carrier#
A voice agent needs more than a phone number. Before you compare per-minute prices, check five things, because they decide whether a cheap carrier is cheap in practice:
- A way to get audio to your agent. Either a SIP trunk into a platform such as Vapi, Retell, LiveKit or Pipecat, or a WebSocket media stream into your own server. Some carriers charge for the stream; some include it.
- A managed AI bridge, if you want one. Twilio ConversationRelay, Telnyx Conversation Relay, Sinch Voice Relay and similar products handle speech-to-text, text-to-speech and interruptions, and you supply the LLM. They cost far more per minute than the call itself.
- Points of presence near your callers and your model. Every extra network hop adds delay before the agent answers.
- Caller ID trust. STIR/SHAKEN "A" attestation on outbound calls, which carriers grant only after they verify your business. Without it, outbound AI calls are more likely to show as "Spam Likely".
- Texting rules. If the agent also sends SMS from a US local number, you need A2P 10DLC registration, which has fees of its own (table below).
US prices side by side#
| Carrier | Inbound local, per min | Outbound local, per min | Local number, per month | Toll-free number, per month | SIP trunking |
|---|---|---|---|---|---|
| Twilio | $0.0085 | $0.0140 | $1.15 | $2.15 | $0.0040/min (SIP interface, BYOC) |
| Telnyx | $0.002 + SIP from $0.0032 | $0.002 + SIP from $0.005 | $1.00 | $1.00 | From $0.0032/min in, $0.005/min out |
| Plivo | $0.0055 | $0.0115 | $0.50 | $1.00 | $0.0028/min in, $0.0046/min out |
| Bandwidth | $0.0055 | $0.0100 | Not listed | Not listed | Quote only |
| SignalWire | $0.0066 | $0.0080 | $0.50 | $0.80 | $0.003/min |
| Vonage | Not readable (see note) | Not readable | Not readable | Not readable | Yes, rates not readable |
| Sinch | Not published (widget) | Not published (widget) | Not published | Not published | US and Canada only |
- Billing increments differ. Bandwidth bills in 6-second increments and Vonage per second from answer, per their own pages. Twilio's page does not state an increment. Short calls cost noticeably less with per-second billing.
- Vonage: its voice pricing page sat behind a Cloudflare challenge for us, and its pricing hub shows a PSTN-leg figure without naming a country. Vonage prices US outbound by number-prefix group. Ask for the rate card before you compare.
- Sinch: the pricing widget showed $0.00 numbers and "from $0.01/min", and Sinch's own FAQ labels its example rates "illustrative". Treat Sinch as quote-based.
- Toll-free inbound costs more everywhere: $0.0220/min on Twilio, $0.0180 on Plivo, $0.0147 on SignalWire.
Streaming, AI bridges and built-in agents#
| Carrier | Media streaming to your server | Managed AI bridge (you bring the LLM) | Own AI agent product |
|---|---|---|---|
| Twilio | Media Streams, $0.0044/min | ConversationRelay, $0.07/min plus voice minutes | No separate priced agent product listed |
| Telnyx | WebSocket streaming, $0.0035/min | Conversation Relay, $0.05/min | AI Assistants, $0.05/min (see note) |
| Plivo | Audio streaming included at no extra charge | Not listed | AI Agent, $0.03/min excluding telephony |
| Bandwidth | $0.0035/min one-way, $0.004/min bidirectional | Maestro orchestration, no public price | No |
| SignalWire | Audio stream or tap, $0.003/min | Not listed separately | AI Agent, $0.16/min on top of the call |
| Vonage | WebSocket price not found | Not listed | AI Studio: no public price for Standard or Advanced; service packs from $3,300/month |
| Sinch | Streams, public preview, no price | Voice Relay, public preview, no price | No |
Two details matter here. Telnyx contradicts itself on what its $0.05 AI Assistants minute includes: its AI pricing page says orchestration, speech-to-text and text-to-speech, with the LLM and telephony billed separately and calls rounded up to a full minute, while its machine-readable rate card says SIP and LLM inference are included. Budget for the narrower reading until Telnyx confirms. And SignalWire's $0.16 agent minute is the most expensive built-in agent here, but it includes the runtime on the same network as the call.
What 10,000 minutes a month costs on each carrier#
This is the cost of the phone leg only, for a setup where the carrier streams call audio to your own agent server. It excludes speech-to-text, the LLM, text-to-speech and your agent platform, which usually cost several times more. If you connect over SIP to a platform like Vapi or Retell instead, drop the streaming column and use the SIP rate.
| Carrier | 10,000 inbound minutes + streaming + 1 number | 10,000 outbound minutes + streaming + 1 number |
|---|---|---|
| Plivo | $55.50 (streaming included) | $115.50 |
| Telnyx | $88.00 | $106.00 |
| Bandwidth | $95.00 (number price not listed) | $140.00 (number price not listed) |
| SignalWire | $96.50 | $110.50 |
| Twilio | $130.15 | $185.15 |
For scale: ElevenLabs Agents charges $0.08 a minute and Retell $0.055 a minute before the model and voice. The carrier is usually under 10% of what an AI phone call costs, so switching carriers saves real money only at high volume. Our voice agent platform comparison breaks down the rest of the bill.
Regions, latency claims and caller ID trust#
- Twilio: eight named edge locations (Ashburn, Umatilla in Oregon, Dublin, Frankfurt, Sao Paulo, Singapore, Sydney, Tokyo) plus a "roaming" option that picks the closest. No latency figures. Outbound A attestation needs an approved Business Profile and a SHAKEN/STIR Trust Product, which Twilio says take about 24 and 72 hours to vet; without them, calls go out with C.
- Telnyx: owns its IP network and says its AI agents answer in under 200 ms, with GPUs placed next to its telephony points of presence; licensed in 45+ countries. Those are Telnyx's claims; we did not measure them. Numbers you own on Telnyx get A attestation, other numbers B.
- Plivo: seven points of presence (California, Virginia, Frankfurt, Mumbai, Singapore, Sydney, Sao Paulo). A attestation when the caller ID is a Plivo number on the same account, otherwise B or C.
- Bandwidth: a US carrier with its own network: four major US points of presence, eight "SuperPOPs", about 70 countries. Direct enterprise customers get A attestation automatically on numbers assigned in Bandwidth's app.
- SignalWire: every number starts at C attestation; A or B only after vetting, requested through a support ticket.
- Vonage and Sinch: Vonage tells Voice API and SIP users to apply for "enhanced trust"; Sinch's elastic SIP covers only the US and Canada.
Texting from the same number: A2P 10DLC fees#
If your agent sends text messages from a US local number, every brand and use case must be registered with The Campaign Registry. Twilio passes the registry fees through "with no added cost"; Bandwidth charges roughly double.
| Fee | Twilio (registry pass-through) | Bandwidth |
|---|---|---|
| Brand registration | $4.50 (Sole Prop, Low Volume Standard); $46 Standard, including secondary vetting | $9 |
| Secondary vetting | $41.50 | $83 |
| Campaign vetting | $15 per campaign | Not listed separately |
| Monthly campaign fee | $10 Standard, $1.50 low-volume mixed, $2 Sole Prop | $20, three-month minimum; no Sole Prop |
Telnyx passes registry fees through and lists a $30 monthly fee for agent and franchise campaigns, plus a $50 one-time T-Mobile campaign fee on its rate card. If your product gives a number to each of your customers, each customer is its own brand, so these fees repeat per customer.
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Getting started: trials and verification#
- Twilio: free trial for 30 days with 75 voice minutes; calls only to up to five verified numbers, in your sign-up country.
- Telnyx: a "pretrial" account gets one US local number (reclaimed after 30 days unless you upgrade), calls only to and from your verified number, 10 outbound calls a day of up to 10 minutes each. Telnyx also has a sign-up API that lets an AI agent create a trial account itself; full KYC applies later.
- Plivo: $10 free credit on pay-as-you-go.
- SignalWire: trial accounts get one number and can call only verified numbers. Leaving trial needs a card and a $5 top-up, and SignalWire's docs say auto top-up then cannot be switched off. That is the main friction point we found.
- Bandwidth, Vonage, Sinch: sales-assisted for anything beyond testing; expect business verification before production traffic.
Or skip the carrier: platforms that include the number#
Most teams building one agent never sign a carrier contract. The voice agent platforms buy numbers on Twilio, Telnyx or Bandwidth and resell them, or connect yours:
| Platform | Phone number | Platform price | Catch |
|---|---|---|---|
| Vapi | 1 free US number on pay-as-you-go (5 on Core at $29/month, 10 on Pro) | $0.05/min plus providers at cost | Free numbers are inbound only, US area codes only, cannot be ported out |
| Retell AI | $2/month local, $5/month toll-free, US and Canada | $0.055/min, plus $0.015/min telephony; $0.07 to $0.31/min all-in by Retell's range | Card required to buy a number |
| Bland AI | Inbound number included on Start (Bland values it at $15/month) | $0.14/min Start; $0.12/min on Build ($299/month) | 100 calls a day on Start |
| ElevenLabs Agents | Import a Twilio number or connect a SIP trunk | $0.08/min plus the LLM | ElevenLabs states no telephony fee of its own; your carrier bills you |
| ElevenLabs Reception | 1 number included | $29/month for 75 minutes | A no-code receptionist, not a developer platform |
If you are choosing between those platforms rather than carriers, see our voice agent platform comparison and Vapi alternatives. If what you actually want is a receptionist for one business, read the best AI receptionist software first: it is cheaper than building.
Which Twilio alternative fits#
- Lowest published per-minute cost with your own agent server: Plivo (streaming included) or Telnyx. Telnyx if you also want a carrier-run AI layer and an agent self-sign-up API; Plivo if you want the lowest number rental.
- Large US volume, carrier relationship, enterprise contracts: Bandwidth. Its 10DLC fees are higher than pass-through, and its number and SIP prices are quote-only.
- An agent runtime on the same network as the call: SignalWire, at $0.16/min for the agent. Watch the trial and top-up terms.
- Already a Vonage or Sinch customer: ask for the rate card; neither publishes US voice rates in a form we could read, and Sinch's AI relay is still in preview.
- Staying on Twilio: reasonable if you already use its messaging, Studio or Flex. Use SIP to an agent platform instead of Media Streams plus ConversationRelay if cost matters.
- One agent, no telephony work: Retell or Vapi for developers; ElevenLabs Reception or another AI receptionist for a business owner.
Calling people rather than answering? AI voices count as "artificial" voices under US law, so outbound calls need prior consent. Our AI outbound calling guide and phone numbers for AI agents cover the rules. For SMS, verification, video and other non-voice Twilio uses, see our Twilio alternatives page, which compares nine providers on prices checked November 11, 2026.
Frequently asked questions#
What is the cheapest Twilio alternative for AI voice agents?#
On published US list prices checked November 11, 2026, Plivo and Telnyx. Plivo charges $0.0055 a minute inbound with audio streaming included and $0.50 a month per local number; Telnyx charges $0.002 a minute plus a SIP leg from $0.0032, $0.0035 for streaming and $1 a month per number. Twilio charges $0.0085 inbound plus $0.0044 for Media Streams.
Does Telnyx have an alternative to Twilio ConversationRelay?#
Yes. Telnyx Conversation Relay costs $0.05 a minute against $0.07 for Twilio ConversationRelay, and Telnyx also sells AI Assistants at $0.05 a minute. Telnyx's own pages disagree on whether the LLM and telephony are included in that AI Assistants price, so budget for them separately.
Which carriers give A attestation for STIR/SHAKEN?#
All of them can, after verification and only for numbers on your account. Twilio requires an approved Business Profile and SHAKEN/STIR Trust Product; Telnyx and Plivo give A for numbers you own on their network; Bandwidth gives A automatically to direct enterprise customers; SignalWire starts every number at C until you are vetted.
Do I need A2P 10DLC registration for an AI voice agent?#
Only if it sends text messages from a US local number. Voice calls alone do not need it. Registration costs a $4.50 brand fee (or $46 with vetting), $15 per campaign and $1.50 to $10 a month per campaign through Twilio's pass-through pricing; Bandwidth charges more.
Can I get a phone number for an AI agent without a carrier account?#
Yes. Vapi includes one free US number on pay-as-you-go (inbound only), Retell sells numbers for $2 a month, Bland includes an inbound number on its Start plan, and ElevenLabs Reception includes a number in its $29 plan.