Answer
Should you require a phone number on your enquiry form?
Ask for it, do not require it. Requiring it costs you the enquirers who did not want to be called yet.
Ask, do not require. A phone number materially improves reachability, and requiring it removes enquirers who deliberately chose a written channel — often the researchers early in a decision who convert later.
This is a genuine trade rather than a settled question, which is why it keeps recurring. A phone number is worth real money: it is the fastest route to a conversation, it works when email is filtered, and speed of contact is one of the few reliably decisive variables in whether an enquiry converts. Requiring it therefore improves your position with everyone who completes the form.
The cost is on the other side of the completion. A number of people choosing a written channel are doing so deliberately. They are at work, they are early in a decision and not ready to be sold to, they are gathering options and do not want three phone calls. Asking them to hand over a phone number before any contact exists is asking them to accept a call they have not yet decided they want, and a share of them will simply leave.
Which group is larger depends on what you sell and where you are in the customer's process, and that dependence is why a general rule fails. Urgent services attract callers who want to be called and are frequently phoning anyway. Considered purchases, professional services and anything with a long research phase attract people who are deliberately keeping distance. The same required field is nearly free in the first case and expensive in the second.
The design that resolves it is unglamorous: ask for the number, do not require it, and say why you want it. A short line explaining that a number lets you answer faster, with an assurance about what you will not do with it, recovers most of the completion rate that requiring it would have cost. People give information readily when the reason is stated and the ask is honest; they resist when it appears to be a condition of being helped.
Preferred-contact-method is the field worth adding alongside it, and it is more useful than either. Someone who supplies a number and selects email has told you something specific, and calling them anyway is a small breach that colours the whole relationship. Someone who supplies a number and selects phone has effectively invited the call, which is the strongest signal on the form and one that most businesses never capture.
There is a compliance dimension that argues for the same design. Rules on calls and texts to mobile numbers depend on the basis on which the number was provided, and a number surrendered because a form would not submit otherwise is a weaker basis than one given freely with a stated purpose and a visible preference. Designing the field honestly is not only better for conversion; it also puts the business on firmer ground for what it does next.
Requiring a phone number is asking a stranger to accept a call before they have decided they want one, and a meaningful share of them decline by leaving.
Answer Production Engine, Context Theory
Related questions
What if we cannot help without speaking to them?
That is a strong reason to ask and still a weak reason to require. Say it plainly on the form — that this kind of work needs a short conversation to scope — and most people who intend to proceed will supply the number. The ones who will not are usually not ready yet, and an email exchange that ends with them offering the number later is a better outcome than a form they abandoned.
Do required phone fields increase fake numbers?
They do, which is the quiet cost that makes the trade worse than it appears. A required field that someone does not want to fill produces a string of digits rather than an abandonment, and the enquiry then looks complete while being unreachable. That is worse than an honest blank, because it consumes a follow-up attempt and looks like a real contact in every report.
METHOD
Every figure below carries its source and the date it was verified. Nothing on this page is asserted.
The numbers on this page.
| What | Value | Specific to |
|---|---|---|
| Odds of making contact — replying within 5 minutes vs within 30 | 100× | Category-wide |
| Firms that never responded to a web enquiry at all | 23% | Category-wide |
| Close rate — response under 5 minutes vs over 24 hours | 32% vs 12% | Category-wide |
Oldroyd, J. B. — MIT / InsideSales.com Lead Response Management Study (2007) · the original five-minute finding; contact, not qualification · verified
Oldroyd, McElheran & Elkington, "The Short Life of Online Sales Leads", Harvard Business Review (March 2011) · 1.25M inbound leads across 2,241 US firms · verified
Optifai speed-to-lead benchmark · n=939 companies · Q2 2025–Q1 2026 · verified
What is specific to this page.
| Kind | Claim | Check it against |
|---|---|---|
| Buying behaviour | Enquirers choosing a written channel frequently do so deliberately — at work, early in a decision, or avoiding sales calls — so requiring a number asks them to accept a call before they have decided they want one. | Form abandonment measured at the phone field, compared against abandonment at other fields in the same form. |
| Workflow | A stated reason for requesting a number, together with an assurance about use, recovers most of the completion rate that requiring the field would have cost, because resistance is to the condition rather than to the request. | Completion rates for an optional phone field with an explanation against a required field on the same form. |
| Workflow | A preferred-contact-method field carries the strongest signal on an enquiry form, since a number supplied alongside an explicit phone preference is an invitation while the same number alongside an email preference is not. | Conversion rates split by whether the enquirer's stated channel preference was honoured on first contact. |
| Constraint | The basis on which a mobile number was provided affects what contact is permitted, and a number surrendered because a form would not otherwise submit is a weaker basis than one given freely with a stated purpose and preference. | The consent language displayed at the point the number is collected, against the contact the business subsequently makes. |
Each row would be wrong on another industry's page. Where a sourced figure exists it is in the table above instead; these are the constraints that shape the work and do not happen to be numbers.
Start with the measurement.
Reading about a benchmark is not the same as knowing your own number. The audit produces yours, measured rather than estimated.
$497 · delivered in 5 business days · credited against month one