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Resources / Comparisons / Vapi
Unibound vs Vapi.
Vapi gives developers the plumbing for a voice agent and passes the speech and model costs through. Unibound is the finished system around the call: WhatsApp, text, email and web chat in the same flow, the rules, the inbox and your team's calls. Vapi's headline minute is lower, before the speech, the model and a phone line are added. Unibound covers more of the job.
Channels, flows and people, side by side
Three things set these apart: which channels each covers, whether one flow joins them, and whether your own team can work in it.
| Vapi | Unibound | |
|---|---|---|
| Built for | Developers and agencies | Firms that want the finished system |
| AI phone calls | In and out | In and out. Calls nobody answers are free |
| SMS | Only when the customer texts first | Yes: sent by a flow, written by AI, and two-way |
| Not offered as a channel | Yes, on your own WhatsApp business account | |
| Not offered as a channel | Yes, from your own domain | |
| Web chat | Yes, a chat and voice widget | Yes, a widget for your website |
| A flow across channels | No. The Workflows builder was retired in August 2026; campaigns are calls that run once | Yes. Calls, messages, waits and people are steps, and each result has its own next step |
| Your team makes and takes calls in it | No. Calls are transferred to a phone number | Yes: browser calls, a call queue, dialling sessions and calls routed to teams |
| A person takes over from the AI | A call transfer, without the transcript | Yes, in one inbox and one call queue, and can hand back |
| Cost per booking | Not found | Yes. Every flow has a goal and a cost for each contact who reached it |
| Where data is held | An EU region with the Premier package only | Customer records are stored in London |
| How you pay | By the minute, in dollars, with several line items | A monthly fee plus usage, in pounds |
One call, or everything that follows it
Most leads are not won on the first call. They are won on the text after a missed call, the call back at the time they asked for, the answer to a question two days later. Vapi is built around a single conversation. Its campaigns ring a list once, by phone, and anything after the call is done with webhooks your developer writes. Its visual Workflows builder was retired in August 2026.
In Unibound every step ends in a result, and each result leads to its own next step, on whichever channel fits. You draw that once and it runs for every contact.
| What happened | What Unibound does next |
|---|---|
| They answer and want to go ahead | Books the appointment and stops the chasing |
| They ask to be called later | Waits until the time they asked for, then rings again |
| Nobody answers | Sends a WhatsApp or text, waits for a reply, and tries again the next morning |
| They reply with a question | The AI answers from your own material, on the channel they used |
| They ask for a person | Puts them in your team's queue with the whole history |
| They say no, or opt out | Stops, on every channel |
The problem you are trying to fix
Most firms looking at these tools have the same few problems. This is what each does about them.
| The problem | On Vapi | With Unibound |
|---|---|---|
| New enquiries wait until someone is free | Your developer triggers the call. A campaign runs once, with no retry schedule. | Point your form or CRM at a flow. It rings within seconds and tries again on the schedule you drew. |
| Most people answer a message before a call | Texts only work when the customer writes first: the assistant cannot send the first message. No WhatsApp or email channel is listed. | The flow moves to WhatsApp, text or email after a missed call and waits for a reply. |
| Your team needs to step in | The call is transferred to a phone number. Vapi's docs say the person receiving it does not get the transcript. | Your team has an inbox, a call queue and browser calls, with the transcript, and can hand back. |
| Calls must respect hours and opt-outs | A campaign has one time zone and one calling window for every contact. There is no built-in do-not-call list. | Opt-outs, calling hours in the contact's own time zone, daily limits and spend are checked before every call and message. |
| Every change needs a developer | Yes. Agents and hand-offs are configured in code. | Open the diagram, change the step, test it on your own phone. |
What each costs
| Vapi | Unibound | |
|---|---|---|
| Platform | From $0 or $29 a month. The Pro plan has a $999 a month minimum. Extra lines $10 a month | No monthly fee on pay as you go for one user. Team plans £500 to £1,500 a month, for 5 to 50 users |
| AI call minutes | $0.05 a minute for hosting, plus speech recognition, the language model and the voice at cost, plus telephony | 16p a started minute, everything included |
| Unanswered calls | Not stated on the pricing page | Free |
For 450 AI minutes a month Vapi comes to roughly £40 to £55 including a UK phone line, plus its plan fee. On Unibound the same minutes are £72, with no monthly fee on pay as you go for one user. Vapi's minutes cost a little less. The other channels, the retries and your team's side are yours to build.
Checked on Prices and features come from each company's own pages, listed under Sources. Prices exclude VAT. Where we say something was not found, we looked on those pages and did not see it; products change, so check before you decide.
Which suits you
Vapi is the better choice if
- You have developers and want to own every part
- Voice is one feature inside your own product
- You want to swap speech and language models freely
Unibound is the better choice if
- You need WhatsApp and email around the calls, on UK numbers
- Your own people must make and take calls alongside the AI
- You want to change the process without a developer
- You want the calling rules handled for you
Questions people ask
Is Unibound an alternative to Vapi?
Yes, if what you want is leads called and followed up on every channel. Vapi is a platform for building a voice agent. Unibound is the working system, with the channels, the team workspace and the rules already there. If you are building your own product, Vapi is the closer fit.
Is Unibound built on Vapi?
No. Unibound runs its own voice service on OpenAI's voice model and Twilio phone lines.
How does Unibound's 16p a minute compare?
The 16p includes the UK phone line, the AI, the transcript, the recording and the summary, and you pay nothing when nobody answers. Vapi's own calculator comes to $0.08 to $0.13 a minute without the phone line, which is about 9p to 12p with a UK line. Unibound bills by the started minute and Vapi by the second, so very short calls cost less there.
Does Vapi have a flow builder?
Not any more. Vapi's docs say its Workflows builder was retired on 18 August 2026 and existing workflows no longer run. Its replacement, Squads, passes one conversation between assistants. It does not run a follow-up over several days or channels.
Sources
- Vapi, pricing. vapi.ai
- Vapi docs, SMS chat. docs.vapi.ai
- Vapi docs, outbound campaigns. docs.vapi.ai
- Vapi docs, Workflows migration. docs.vapi.ai
- Vapi docs, transfer call. docs.vapi.ai
- Vapi docs, EU region. docs.vapi.ai
- Twilio, UK voice pricing. twilio.com
- Unibound, pricing. unibound.ai
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