Best AI Phone Agent APIs for Developers in 2026: Vapi, Retell, Bland, and More

Per-minute prices are list prices, and some platforms add telephony, model, voice, or add-on fees, so a production call can cost more than the headline rate. Check the linked page before you budget.

An AI phone agent API places real outbound calls over the public phone network, runs a realtime voice conversation with whoever answers, and returns a result your code can read: the network outcome, a transcript when present, and temporary recording access when available.

The products in this space split into two groups. Platforms such as Retell AI, Vapi, Bland AI, Synthflow, and Telnyx Voice AI give you the parts: you choose or configure the model, the voice, the telephony, and the conversation design, and you build the agent. A finished calling product gives you the agent: you send a phone number and a goal, and it handles the call.

So the buyer’s question is not only “which API is best” but “do I need to own the voice layer?” If voice is your product, you probably do, and the platforms are built for that. If a call is one step in a larger task, such as a coding agent calling a vendor or an assistant booking a dentist, you probably do not.

Retell AI is a pay-as-you-go platform for engineering teams building custom voice agents. Its pricing page lists $0.07 to $0.31 a minute, with no contract to start.

The price is the sum of parts you choose. Retell lists its voice infrastructure at $0.055 a minute, its own and several third-party voices from $0.015 a minute, telephony through Twilio at $0.015 a minute, and language models from under a cent to $0.32 a minute at standard speed, depending on the model. Pay as you go includes 20 concurrent calls, call analytics and transcripts, simulation testing, webhooks, and API access. Enterprise plans add custom pricing, a dedicated server option, and an uncapped number of concurrent calls.

Pick Retell when you are building a voice product, want to choose the model and voice per agent, and have engineers to own the prompts and tools. A support line that answers thousands of calls a day with your own logic is a good fit. A single “call the dentist” step inside an AI agent is more than Retell needs to be.

Bland AI sells hosted voice agents with the model, speech-to-text, and voice bundled into one per-minute rate. Its pricing page lists two self-serve plans:

• Start: $0.14 a minute, no platform fee, up to 10 concurrent calls and 100 calls a day.
• Build: $0.12 a minute plus $299 a month, up to 50 concurrent calls and 2,000 calls a day.

Transfers cost extra per minute, and Enterprise is priced to your volume. Bland states there are no token charges or model pass-through fees, which makes per-call cost easier to predict than on platforms that bill each provider separately.

Bland also sells a separate Agent Phone Plan that gives one personal AI agent its own US number for $29.99 a month, with one call at a time and calls limited to the US and Canada.

Pick Bland when a team needs high-volume outbound or inbound flows, wants one bundled rate, and has engineers to maintain the agent configuration.

Vapi is an orchestration layer for teams that want to choose every component. Its pricing page charges $0.05 a minute for hosting and passes model, transcription, voice, and telephony costs through at the providers’ rates. Plans start free with one Vapi phone number, then Core at $29 a month with five numbers and Pro at $999 a month with ten.

The cost of that flexibility is integration surface. You manage relationships with a model provider, a transcriber, a voice vendor, and a telephony carrier, each with its own pricing and outages. For a team whose product is voice, that control is the point. For a developer adding phone calls to an existing agent, it is extra work.

Pick Vapi when you have strong opinions about each layer of the voice stack and want to swap providers per assistant.

A few more platforms come up in the same evaluations:

• Synthflow now sells enterprise contracts that start at $30,000 a year, priced on call volume, concurrency, and integrations. It fits enterprises that want a builder and launch support, not a solo developer.
• Telnyx Voice AI runs agents on Telnyx’s own telephony network. Its pricing page lists $0.05 a minute for the voice engine, with LLM tokens and telephony billed separately, and US local numbers from $1 a month. It fits teams already using Telnyx.
• Vocode is an open-source library for building your own voice agents across phone, web, and Zoom, for teams that want to self-host.
• PolyAI prices per minute through sales for enterprise contact centers.

All of these are reasonable foundations for a voice product. None is a finished agent that your existing AI assistant can hand a call to without a build.

ClawCall is our product. It is a finished calling agent: it dials US numbers, navigates phone menus, waits on hold, talks to whoever answers, and returns the outcome with a transcript when present. For agent hosts, the preferred connection is hosted OAuth MCP: sign in, approve the call scopes, and the host discovers the calling tools without you copying an API key. The packaged skill and REST API are fallbacks for hosts without remote MCP.

The REST contract is small. POST /call returns a call_id immediately. You poll GET /call/:id until lifecycle reaches finalized, then read outcome plus the nullable talk_seconds, transcript, and recording_url fields. The first anonymous POST /call returns a proto-key, and that key keeps working after sign-up. The API tutorial walks through it in cURL, Python, and Node, and ClawCall’s AI phone call API page covers what it handles.

Fixed product rules: it discloses that it is an AI when asked, leaves voicemail only when instructed, and does not send bulk or robocall-style promotions, while individual outreach calls are allowed.

Pricing is flat: Unlimited at $4.99, Unlimited Reserve at $8.99, and Unlimited Reserve Plus with an inbound AI assistant at $14.99, after a free trial of 30 calls and 30 minutes, whichever lasts later. Every plan allows one outbound call at a time per account. Trial and Unlimited calls use shared lines. A second call while one is running returns concurrent_call_limit. Wait for the current call to finalize before placing the next. If all shared lines are busy with other accounts, number_pool_exhausted means you can retry shortly. Unlimited Reserve and Reserve Plus calls always use your reserved number, one call at a time. On shared-pool calls, looping you in uses a second shared line while connected. ClawCall deletes transcripts 7 days after a call ends and recordings 10 minutes after a call ends, and a call can finish without a transcript.

A newer group of products gives an AI agent its own phone number instead of a voice-agent platform:

• AgentPhone provisions US and Canadian numbers for AI agents. Its docs list $3 a month per number and $0.13 to $0.22 a minute for voice.
• AgentLine sells US numbers at $2 a month and calls at $0.10 a minute.
• Bland’s Agent Phone Plan gives one agent a US number with unlimited US and Canada calls for $29.99 a month.

These fit when you want your agent to own a number for inbound calls and texts. Other tools that show up in the same searches do something else: ClawTalk is an iOS voice front-end for your own OpenClaw agent, ClawdTalk gives an OpenClaw bot an inbound number, and PollyReach is an agent skill that gives an AI agent its own phone number to place and answer calls. For consumer apps that call businesses for you, see the consumer comparison.

Most developers comparing these tools sit somewhere between build and buy without having named it.

At the build end, voice is your product and you will maintain the stack. Pick Retell AI, Vapi, or Bland AI, plan for a multi-week integration, and accept per-minute pricing as a cost of the business.

At the buy end, you are building an AI agent in Claude Code, Cursor, ChatGPT, or your own framework, and a phone call is one step in a task. You do not want to design conversation flows or wire SIP. You want the agent to have a phone the way it has a browser.

That second case is what ClawCall was built for. Hosted OAuth MCP is the shortest path from intent to dial tone in a compatible host, and the REST API covers custom code. If you are in the first case, the platforms above are the honest recommendation.

If you have an afternoon and want a decision, use the same method for every tool:

1. Define one realistic call: book a dentist appointment, dispute a $40 utility charge, or wait on hold with an airline.
2. Write down what success looks like: a confirmation number, a callback time, a quoted price.
3. Run the same task on two or three tools and compare what each returns.

On the finished-product path, connect hosted MCP in Claude Code or Cursor, hand your agent the task in plain language, and let it place the call. After lifecycle is finalized, read the transcript when present. The first run draws from the free trial.

On a platform, the same run means building the agent first: choose a voice, write the prompt, connect telephony, deploy. That is what platforms are for, and the time difference is the point. If your question is “which tool gets my agent a working phone this afternoon,” the comparison ends early. If it is “which tool will I build a voice product on for five years,” it is worth the week.

• Retell AI pricing
• Vapi pricing
• Bland AI pricing
• Bland AI Agent Phone Plan
• Synthflow pricing
• Telnyx Voice AI pricing
• PolyAI pricing
• AgentPhone docs: Usage and billing
• AgentLine pricing