AI voice agent or phone menu: which should a small business use?

Short answer

A phone menu (IVR) is the cheaper choice in 2026 for a small business that only needs to route callers to a few teams. On Twilio it costs about $0.01 a minute for inbound UK calls, plus $0.0025 a run after 1,000 free runs a month. An AI voice agent suits callers with varied questions or bookings and costs $0.07 to $0.31 a minute on Retell before telephony. You can run both, with the AI answering one branch of the menu.

Deniz SancarFounder of Yarigai, London. Updated 7 November 2026.

Yarigai is a done-for-you AI agency that builds these systems, so read this with that in mind. Every price and figure links to its source below. Read this page as Markdown.

At a glance

Question	Answer
Inbound minute on a UK Twilio number	$0.0100 for local or mobile numbers (USD, current as of August 2026)
UK local number on Twilio	$3.50 a month
Twilio Studio flow to run a menu	1,000 runs a month free, then $0.0025 a run (October 2026)
Speech recognition in a menu	$0.02 per use on Twilio's default provider
AI voice agent on Retell	$0.07 to $0.31 a minute, plus $0.10 a minute for a UK number bought through Retell
Twilio ConversationRelay for an AI voice agent	$0.07 a minute, plus call and model costs
Business phone plan with one auto attendant	From £13.95 per user a month (The VoIP Shop)
Custom AI voice agent build	From £8,000 plus £499 a month (Softomate, October 2026)
UK consumers who had left a business over an automated menu	51% (Vonage survey of 2,009 people, 2019, vendor data reported by Call Centre Helper)

What is the difference between a phone menu and an AI voice agent?

A phone menu plays fixed prompts and routes the call by keypad press or a short spoken word. An AI voice agent listens to what the caller says, decides what to do and talks back.

Phone menu (IVR)

IVR stands for interactive voice response. The caller hears "press 1 for sales, press 2 for accounts", and each press moves them down a fixed tree to a team, a recorded message or voicemail. A speech-enabled menu lets callers say "accounts" instead, which costs $0.02 per use on Twilio's default speech provider. The menu never goes off the tree, which makes it predictable and cheap.

AI voice agent

An AI voice agent turns the caller's speech into text, sends it to a language model and reads the reply aloud. It can answer questions in the caller's own words, book an appointment, look up an order and then transfer to a person. Anthropic describes agents as systems where language models "dynamically direct their own processes and tool usage", and that freedom is what makes a voice agent flexible and less predictable than a menu.

AI voice agent and phone menu compared

A menu wins on cost and predictability, and an AI voice agent wins when callers ask questions a menu can't list. The table sets them side by side.

	Phone menu (IVR)	AI voice agent
Caller experience	Fast for two or three clear choices. In Vonage's 2019 UK survey, 43% complained that their reason for calling isn't listed and 37% that menus are too long	Callers speak normally. In Gartner's 2024 survey, 64% of customers would prefer companies didn't use AI for customer service
Cost per minute, USD	About $0.01 inbound on Twilio, plus $0.0025 a run after 1,000 free a month	$0.07 to $0.31 on Retell plus $0.10 UK telephony, or $0.07 on Twilio ConversationRelay plus $0.01 inbound and the model
Set-up	Included in some business phone plans, such as one auto attendant from £13.95 per user a month at The VoIP Shop	A project. Softomate lists a GoHighLevel AI receptionist from £2,000 and a bespoke voice agent from £8,000
Monthly upkeep	Change the prompts when teams or hours change	Read transcripts, update the information it answers from, test after model changes
Typical failures	Wrong branch, menu loops, out-of-date options, callers pressing 0 to escape	Mishearing names and numbers, a confident wrong answer, a wrong booking, pauses while it thinks
Who answers for mistakes	You	You. A Canadian tribunal ordered Air Canada in February 2024 to pay a customer over wrong information from its website chatbot
Best for	Routing to a few teams, opening hours, out-of-hours messages	Varied questions, bookings, order lookups, after-hours and overflow calls

The caller numbers on both sides come from vendor or analyst surveys, as reported by Call Centre Helper (Vonage) and DIGIT (Gartner), and this guide found no independent study of hang-up rates for AI voice agents.

What each option costs to run

On the same call volume, an AI voice agent costs roughly 7 to 37 times as much per month as a menu on Twilio. The example below assumes 1,000 inbound calls a month at 3 minutes each, which is 3,000 minutes. Swap in the numbers from your own phone bill.

Option	Monthly cost, USD	Working
Phone menu on Twilio Studio	$33.50	3,000 minutes at $0.0100 is $30.00, plus a $3.50 local number. 1,000 flow runs fit inside the free allowance
Phone menu with speech recognition	$53.50	Adds 1,000 speech uses at $0.02
AI voice agent on Twilio ConversationRelay	$243.50, plus model usage	3,000 minutes at $0.07 is $210.00, plus $30.00 inbound and the $3.50 number
AI voice agent on Retell	$512 to $1,232	3,000 minutes at $0.07 to $0.31, plus $300 of UK telephony at $0.10 a minute and a $2 Retell number

Twilio's UK prices are current as of August 2026 and Retell's were checked on 7 November 2026. Per 3-minute call, the menu costs about $0.03 in call charges and Retell costs $0.51 to $1.23 with UK telephony.

Retell's range depends on the model and the voice. Its voice infrastructure costs $0.055 a minute and its own voices $0.015. The language model adds $0.0064 a minute for GPT 5.4 nano up to $0.08 for Claude 4.6 Sonnet on its Standard tier, so those two builds cost about $0.076 and $0.15 a minute before telephony. Calls on a UK number bought through Retell add $0.10 a minute, and Retell charges nothing for calls over your own SIP trunk.

Two costs apply to both options. Forwarding a call from either one to a staff mobile adds an outbound leg at $0.0305 a minute to a UK mobile on Twilio. Recording on Twilio costs $0.0025 a minute, with storage at $0.0005 a minute a month.

To compare either option with staff time, the guide to AI receptionist costs sets off-the-shelf AI receptionist plans against a part-time receptionist's wages.

When a phone menu is still the better choice

A menu is the better choice when most callers want a person and only need sending to the right one. It also suits calls where a wrong answer costs more than a short wait.

Callers need routing to two to five teams, and the options rarely change.
Most calls come from existing clients who want their account manager by name.
Calls carry risk, such as complaints, emergencies or regulated advice, where a person should answer fast.
Nobody on your team has time to read AI transcripts each week and fix what the agent gets wrong.
Call volume is low enough that the people who answer now aren't stretched.

How to combine a menu and an AI voice agent

Combine them by keeping a short menu and giving one branch, or the out-of-hours line, to an AI voice agent. There are four common ways to split the work.

Menu first, AI on one branch. "Press 1 to book or change an appointment" goes to the AI, and every other option goes to people.
AI first, with an exit. The AI answers, and the caller can say "person" or press 0 at any point to reach staff.
Out of hours and overflow. The menu runs in office hours, and the AI answers after hours and when every line is busy.
AI takes the message. When nobody picks up, the AI records the caller's name, number and reason and logs it for a call back.

Every set-up needs a fast route to a person. In Gartner's survey, 60% of customers worried that AI would make it harder to reach one, and 35% of Vonage's respondents complained that menus waste time and keep them from a live person.

UK rules on call recording, AI disclosure and outbound calls

UK law requires you to tell callers that calls may be recorded, and EU law now requires AI systems that talk directly to people to be designed to tell them they are dealing with an AI. Outbound marketing calls carry stricter rules than inbound calls.

Call recording

Regulation 4 of the Investigatory Powers (Interception by Businesses etc. for Monitoring and Record-keeping Purposes) Regulations 2018 requires that "the system controller has made all reasonable efforts to inform every person who may use the telecommunication system" that calls may be intercepted. A short announcement at the start of each call does this. Treat recordings and transcripts as personal data, and say in your privacy notice how long you keep them.

Telling callers they are speaking to an AI

This guide found no UK rule that requires a phone AI to say it is an AI. The EU AI Act is different. Article 50(1), which applies from 2 August 2026, says AI systems that interact directly with people must be designed so those people are "informed that they are interacting with an AI system", unless that is obvious. If any of your callers are in the EU, disclose. One opening line covers both points, such as "You're speaking to our AI assistant, and this call is recorded."

Outbound calls

The ICO says an automated marketing call is "a call made by an automated dialling system that plays a recorded message", and consent "must specifically cover automated calls". Its page doesn't mention AI voices, so take advice before an AI agent makes marketing calls. For live marketing calls, you must not call numbers on the Telephone Preference Service or Corporate TPS without consent, you "must always say who is calling", and you must display your number.

How Yarigai approaches voice and phone builds

Yarigai is a done-for-you AI agency in London that builds AI agents and lead capture and booking flows inside the client's own accounts. A phone build runs on the client's own telephony and calendar accounts, and the client owns the code, the data and the accounts from day one.

Per-minute pricing makes the running cost the number to check first. AI and hosting bills go to the client at cost, and the monthly running cost is on the quote. The one-week blueprint sets out a written plan, a clickable prototype, that monthly running cost, a fixed price and the payback maths against what answering calls costs today. Yarigai quotes a fixed price after the blueprint, and its guarantee reads "If the build isn't profitable for you, we won't build it."

A person approves anything that sends money, emails a customer or deletes data. See AI customer support or book a scope call.

Common questions

What is an IVR?

IVR stands for interactive voice response, the "press 1 for sales" menu on a business phone line. It routes callers through a fixed tree using keypad presses or short spoken words. On Twilio, a menu flow costs nothing for the first 1,000 runs a month and $0.0025 a run after that, plus call charges.

Is an AI voice agent cheaper than a phone menu?

No. On Twilio, an inbound UK minute costs $0.0100, while an AI voice agent costs $0.07 to $0.31 a minute on Retell before telephony. The fairer comparison is with the staff time or missed calls it replaces, which the AI receptionist cost guide works through.

Do I have to tell callers they are talking to an AI?

UK law has no AI-specific rule for phone calls in what this guide found, but the EU AI Act's Article 50 requires disclosure to people in the EU from 2 August 2026. UK call recording rules already require you to tell callers that calls may be recorded. One opening sentence can cover both.

Will callers hang up on an AI voice agent?

No independent data on AI voice agent hang-up rates exists in what this guide found. Gartner's 2024 survey found 64% of customers would prefer companies didn't use AI for customer service. Menus lose callers too, and 51% of people in Vonage's 2019 UK survey had left a business over an automated menu.

Should a small business add speech recognition to its phone menu?

It helps when the menu has more than a few options or callers often press the wrong key. Twilio charges $0.02 per speech use on its default provider, so 1,000 calls add $20 a month. Keep keypad options as a fallback for noisy lines.

Can an AI voice agent make outbound sales calls in the UK?

Treat it with care. The ICO says automated marketing calls need consent that specifically covers automated calls, and its guidance doesn't address AI voices. Get legal advice before an AI agent makes any outbound marketing call.

Sources

Checked on or before 7 November 2026. Prices change, so check the live page before you decide.

Programmable Voice Pricing in United Kingdom, Twilio, current as of August 2026, checked 7 November 2026.
Serverless Pricing, Twilio, current as of October 2026, checked 7 November 2026.
AI Phone Agent Pricing, Retell AI, checked 7 November 2026.
AI Automation Pricing for UK Businesses: What Every Service Costs and What ROI to Expect in 2026, Softomate Solutions, updated 1 October 2026, checked 7 November 2026.
VoIP Plans and Pricing UK, The VoIP Shop, checked 7 November 2026.
Building effective agents, Anthropic, published 19 December 2024, checked 7 November 2026.
The Investigatory Powers (Interception by Businesses etc. for Monitoring and Record-keeping Purposes) Regulations 2018, regulation 4, legislation.gov.uk, checked 7 November 2026.
Telephone marketing, Information Commissioner's Office, checked 7 November 2026.
Article 50: Transparency Obligations for Providers and Deployers of Certain AI Systems, EU Artificial Intelligence Act website, checked 7 November 2026.
64% of People Don't Want Companies to Use AI in Customer Service, DIGIT, published 9 July 2024, checked 7 November 2026.
IVR Horror Costs Businesses £130 per Customer Each Year, Call Centre Helper, published 25 September 2019, checked 7 November 2026.
Air Canada must pay B.C. man hundreds for chatbot error, Global News, published 15 February 2024, checked 7 November 2026.

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