Before anything else, a warning about the numbers in this market.
Search for the cost of missed calls and you will find that 85% of people whose calls go unanswered never call back, attributed to BT. You will find that 86% of business callers hang up when they reach voicemail, attributed to a Forbes survey. Neither figure exists. The BT research those claims hang on is real, a 2014 study of 1,010 business telecoms users, and it contains no 85% figure anywhere. The Forbes survey appears not to exist at all, and is now being cited by articles that found it in other articles.
What follows uses only figures we could trace to a published source, with the age and method of each stated. Several are older than we would like. That is the state of the evidence.
What voicemail does
It records a message when nobody answers. That is the whole of its function, and it has two consequences.
The caller has to decide whether their question is worth recording, and then wait for you to decide it is worth returning. Both decisions add delay, and the second is invisible to them.
Meanwhile the enquiry sits still. Nothing is booked, answered or qualified.
What the traceable evidence says
Callers give up sooner than firms assume. BT's 2014 research, carried out by Populus among 1,010 business telecoms users and 505 senior managers, found customers would try to call a maximum of twice before taking their business elsewhere. A fifth would call once.
Twelve years old, and about business-to-business telecoms rather than consumers, so treat it as indicative. But it points the same way as everything else here.
Response speed changes the outcome. The clearest evidence is a Harvard Business Review study from March 2011, which audited 2,241 companies by sending each a web enquiry and measuring the reply. It found 37% responded within an hour, 16% within a day, 24% took longer than a day, and 23% never replied at all. Average response time among those who did reply within a month was 42 hours.
A companion analysis of 1.25 million sales leads across 42 companies found firms making contact within an hour were nearly seven times more likely to have a meaningful conversation with a decision maker than those waiting an hour longer, and more than sixty times more likely than those waiting a day.
These are 2011 figures about web enquiries rather than phone calls, and they are frequently misquoted: the seven-times figure comes from the lead analysis, not the 2,241-company audit. Cited properly they show something simple. The value of an enquiry decays quickly, and voicemail is a mechanism for adding delay.
In professional services, there is hard data. Clio's 2024 Legal Trends Report ran a secret shopper study in which a research company contacted 500 law firms. Only 40% answered a call from a prospective client, down from 56% in 2019. Including callbacks, shoppers reached just 52% of firms, so 48% were effectively unreachable by phone even after being left messages. Of the firms that missed a call, only 20% rang back.
That last figure is the one to sit with. Four in five missed calls at those firms were never returned. Voicemail was not a delayed answer. It was no answer.
Callbacks fail too. Hiya's State of the Call 2024, based on 221.3 billion analysed calls and a survey of 12,127 consumers across six countries, found 43% of consumers will never answer a call from an unidentified number and 60% will never ring one back. When you return a voicemail from an office line the caller does not recognise, a good share of those attempts go nowhere.
What answering the call changes
The call is answered. Everything else follows from that.
The caller states their question and gets an answer rather than recording it. An appointment can be booked while they are on the line. Details are captured in a consistent form, so no callback is needed simply to establish the facts. Sales calls get filtered rather than filling your voicemail. It works at nine in the evening and on a Sunday, which is when a good share of enquiries arrive. And you get a transcript and summary rather than an audio file to sit through.
Working out your own number
Rather than borrowing a statistic, calculate it from your own figures. Four inputs: unanswered calls per month, what share were potential new clients rather than existing ones or sales calls, your average matter or engagement value, and your usual conversion rate from enquiry to instruction.
Multiply them. A practice missing 40 calls a month, where half are prospects, converting at 30%, on an average engagement of £1,200, is looking at £7,200 a month of work not captured.
Two honest caveats. Not every missed call is a lost client; some ring back, and some were never going to instruct you. And no answering service converts every call it answers. Halve your figure if you want a conservative version. The conclusion tends to survive it.
Where voicemail still makes sense
Callers who genuinely just need to leave information, where no reply is expected. Very low volume, where two missed calls a month will not justify a subscription. Calls you actively do not want, where voicemail works as a deliberate filter. And as a fallback behind an answered call rather than in front of one.
Voicemail is a poor front door and a reasonable last resort.
The honest comparison
The Clio data is the useful frame. The realistic alternative to an answering service is usually not a person answering perfectly. It is a call that rings out and a message nobody returns.
So the question worth asking is not whether software answers calls as well as your best member of staff. It is whether software answering the call beats nobody answering it. For a phone ringing at eight on a Friday evening, that is a straightforward comparison.
Where it gets less straightforward is the call needing judgement: the distressed caller, the complaint, the enquiry with conditions attached. Clio found 67% of clients still wanted the ability to speak to a person when they needed one. An arrangement that handles volume with software and routes those calls quickly to your own people addresses both problems. Voicemail addresses neither.
Deliberately excluded from this article: the widely circulated 85% never-call-back figure attributed to BT, and the 86% voicemail hang-up figure attributed to Forbes. Neither appears in any traceable primary source.