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Resources / Comparisons / Retell AI
Unibound vs Retell AI.
Retell AI gives developers and agencies an AI phone agent billed by the minute, with a Dialer that runs sequences of calls and texts. 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. Retell's headline minute is lower, before the voice, the model and a UK 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.
| Retell AI | Unibound | |
|---|---|---|
| Built for | Developers and agencies | Firms that want the finished system |
| AI phone calls | In and out. Calls that fail to connect are not billed | In and out. Calls nobody answers are free |
| SMS | US numbers only | 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 | Dialer sequences of calls and texts over days, branching on outcomes. No WhatsApp or email steps | 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 | 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 | The US, with no EU or UK option | 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. Retell's Dialer does run a sequence: calls and texts over several days, with the next step chosen from what happened. Its texts work on US numbers only, so for UK contacts the sequence is phone calls. Retell lists no WhatsApp or email channel, and nowhere for your team to make calls.
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 Retell AI | With Unibound |
|---|---|---|
| New enquiries wait until someone is free | Your developer sends the lead to Retell. The Dialer rings and retries on a schedule you set. | Point your form or CRM at a flow. It rings within seconds, then follows up on other channels. |
| Most people answer a message before a call | SMS is for US numbers only. 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 or SIP address. No softphone, call queue or inbox is described. | Your team has an inbox, a call queue and browser calls, and can take over and hand back. |
| Calls must respect UK hours and opt-outs | An opt-out list is checked before each call. Local calling hours are worked out from US and Canadian area codes, with one fallback time zone for the rest. | Opt-outs, calling hours in the contact's own time zone, daily limits and spend are checked before every call and message. |
| Customer data must stay close to home | Retell says its infrastructure is in the US and that it does not operate services in the European Union. | Customer records are stored in London. You set how long they are kept and can erase a contact on request. |
What each costs
| Retell AI | Unibound | |
|---|---|---|
| Platform | No monthly fee to start. Numbers $2 a month. 20 calls at once, then $8 a month each | 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 | $0.055 for voice infrastructure, plus the voice ($0.015 to $0.10), the language model and the phone line ($0.015 in the US; about $0.03 to a UK mobile on Twilio) | 16p a started minute, everything included |
| Unanswered calls | Not billed. Dialling a list adds $0.005 a call | Free |
For 450 AI minutes a month, with a mid-priced voice and language model, and a UK line, Retell comes to about $63, or roughly £48. On Unibound the same minutes are £72, with no monthly fee on pay as you go for one user. The minutes cost a little less on Retell with a mid-priced setup, and more with a premium voice. The difference is what happens between the calls.
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
Retell AI is the better choice if
- You have developers and want to own every part
- Voice is one feature inside your own product
- Your contacts are in the US, where Retell's texts work
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 Retell AI?
Yes, if what you want is leads called and followed up on every channel. Retell AI 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, Retell AI is the closer fit.
Is Unibound built on Retell AI?
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. Retell prices each part separately: its pricing page gives $0.07 to $0.31 a minute with a US line, which is roughly 6p to 25p with a UK line. Unibound bills by the started minute and Retell AI by the second, so very short calls cost less there.
Does Retell have a flow builder?
Two. Conversation Flow designs what the agent says inside one call. The Dialer runs a sequence of calls and texts for each contact over days. The Dialer has no WhatsApp or email step and its texts work on US numbers only, so it is not a journey across channels for a UK firm.
Sources
- Retell AI, pricing. retellai.com
- Retell AI docs, Dialer. docs.retellai.com
- Retell AI docs, Dialer sequences. docs.retellai.com
- Retell AI docs, SMS. docs.retellai.com
- Retell AI docs, transfer call. docs.retellai.com
- Retell AI docs, compliance. docs.retellai.com
- Twilio, UK voice pricing. twilio.com
- Unibound, pricing. unibound.ai
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