Verify email or phone number: which fits when?
Every sign-up form asks for a contact, and most ask for an email address out of habit. This guide shows what verifying an email address and a phone number each proves, how easily each one multiplies and which one fits your use case, or when you should offer both.
- What each verification proves
- Six use cases at a glance
- Offering both channels
Christian Schätzlein, Founder and developer of Sendity
3 min read
Which contact for which use case?
Use case, what you need, channel
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Newsletter An address you write to Email
The address is what you need later. A sent email proves the inbox and the consent.
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White paper A business contact Email
The company domain tells you more than a phone number.
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Webinar Access link and reminder Both
The link goes by email. A verified number is a second way in when the email lands in spam.
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Giveaway One entry per person Phone
Numbers are much harder to multiply than addresses.
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Free trial One account per person Phone
Starting credit goes to a number, not to the next alias.
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Callback A number that answers Phone
You need the number and nothing else.
Sign-ups by message. No form, no code.
Sendity is a sign-up widget for your website. Instead of filling in a form, your visitors send one short message via WhatsApp or email. Sendity checks who it came from and hands your site the name and the confirmed phone number or email address.
See how Sendity works →-
One message instead of a form Visitors tap send in WhatsApp or their email app. Nothing to type, no confirmation email to click.
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Confirmed by the message itself The contact comes from the sender of the message, so typos and made-up addresses never reach your list.
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Pay per confirmed contact Start with 1,000 free credits, no credit card. After that, prepaid packages with no subscription.
Both show that a contact is real and in the user’s hands. They differ in what you can do with it later and how easily someone gets a second one.
Start with what you need later
If you will send emails, verify the address. If you will call or need one entry per person, verify the number. The GDPR principle of data minimisation points the same way: ask for what you use.
Email: the inbox exists
A verified address shows that the user controls the inbox. That is enough for newsletters and downloads. Aliases, throwaway domains and own domains make a second address free.
Phone: the number is in use
A verified number shows that a phone with this number is in the user’s hands. Numbers are scarce, so they suit one entry per person. Some people hesitate to share their number, especially for marketing.
Verification is not consent
A verified number does not allow you to send advertising via WhatsApp or SMS. Like email marketing, that needs its own consent.
Offering both
With reverse OTP, the visitor sends one message, by WhatsApp or by email, whichever they prefer. You decide per campaign which channels to offer and get the verified contact either way.
Three questions for your form.
Answer them in this order and the channel usually follows.
How will you reach them?
By email, by phone, or not at all after the sign-up.
Does a second entry hurt?
If duplicates cost you prizes, credit or seats, anchor on the number.
How much friction fits?
Where the number feels like too much, offer email alongside and let visitors choose.
Two channels, one step.
How verifying each channel works with a form and with reverse OTP.
| Aspect | Form with confirmation | With Sendity |
|---|---|---|
| Type the address, open the inbox, click the link | Send one prepared email | |
| Phone | Type the number, wait for the SMS, type the code | Send one prepared WhatsApp message |
| Offering both | Two flows to build and maintain | One widget, the visitor picks |
| Typos | Possible in both fields | None: the contact comes from the sender |
What letting visitors choose changes.
You set the rules per campaign, visitors use the channel they trust.
One widget, two channels
WhatsApp and email side by side, without a second flow.
Per campaign
Email only for the newsletter, phone only for the giveaway, both for the webinar.
Verified either way
Whichever channel the visitor picks, the contact comes from the sender.
Live on your page in minutes.
Sendity runs as a compact widget on your page. Pick the path that fits your website.
Email or phone: common questions.
May I ask for a phone number for a newsletter?
Only if you need it. Under data minimisation, ask for what you use, and make anything else optional.
Does asking for the number cost sign-ups?
It can, especially in marketing. Say what you use it for, and offer email as an alternative where one entry per person does not matter.
What about visitors without WhatsApp?
They can use email, or send the code by SMS if you allow it. SMS reaches everyone but is less secure.
Can I get both from one visitor?
One verification gives you one contact: the number or the address the message came from. If you need both, ask for a second step later, when it is worth it.
Keep reading.
Reviewed for accuracy in by Christian Schätzlein.
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