Clickable phone number in email signature: how to build a tel: link that works

A clickable phone number in email signature blocks is a normal link whose address starts with tel: instead of https:, followed by the number in international form, such as tel:+442079460377. On a phone, tapping it should offer to start a call. The format comes from RFC 3966, the tel URI specification, and the iPhone behavior from Apple’s page on phone links. We read both on 5 October 2026.

What a clickable phone number in email signature looks like

There are two parts: what people read and where the link goes.

The visible text can be formatted for people: +44 20 7946 0377. The link address should be compact: tel:+442079460377. In HTML:

+44 20 7946 0377

Apple’s page gives the same pattern for a webpage, 1-408-555-5555, and explains that when someone taps a telephone link on iOS, the system shows an alert asking whether they want to dial. From iOS 10.3, Apple says an alert and a confirmation are also required when an app opens a tel URL. That pause is the system’s, and your signature cannot remove it.

Steps for a clickable phone number in email signature blocks

Microsoft’s Outlook signature page lists links among what a signature can contain and does not mention telephone links. Google’s page on Gmail CSS does not address links at all. Neither gives a tel: example. So treat the following as the general method, and test it in your own app.

1. Type the number in international format in the signature box.
2. Select the number.
3. Use the app’s link tool (usually a chain icon or Insert hyperlink).
4. In the address field, type tel: and the number with no spaces, for example tel:+442079460377.
5. Save, send a test to your phone, and tap.

If you write the signature as HTML, put the a tag around the number as shown above. Our wider guide to adding a link to an email signature covers the same link tool for web addresses and mail links.

Writing the number so the link works

The standard is strict about one thing. RFC 3966 says a global number is identified by a leading plus sign, and that it must be made of the country code and the national number as specified in E.123 and E.164. The ITU’s page for E.164 lists it as “The international public telecommunication numbering plan”, current version 02/26, and we did not find digit-length details on that page, so we do not quote one.

Here is how common mistakes change the outcome:

What staff type	Link address	Problem
+44 20 7946 0377	tel:+442079460377	Correct.
020 7946 0377	tel:02079460377	A local number with no country code. It only works for someone dialing from the same country.
+44 (0)20 7946 0377	tel:+4402079460377	The home-country zero belongs outside the link; remove it.
+234 802 000 0000	tel:+2348020000000	Correct.
+1 415 555 0142 ext. 3	tel:+14155550142	Keep the extension in the visible text only, not in the link.
+1 415 555 0142 #3	not linked	Apple says a # in a tel URL stops the Phone app from dialing.

The RFC does allow visual separators in the number: hyphens, periods and parentheses, and it says they are only there to aid readability and are not used to place a call. It also says spaces are not allowed in URIs. Stripping everything except the plus and the digits is the simplest rule. For a longer treatment of the format itself, see how to write a phone number internationally.

The RFC also covers local numbers, which need a phone-context parameter to say where they are valid. In a signature, avoid them. Your readers are in other countries.

Where a clickable phone number in email signature blocks works

What we can say from the pages we opened:

• iPhone. Apple says tel launches the Phone app, and iOS asks for confirmation before it dials.
• Safari on iOS. Apple says telephone number detection is on by default. Apple’s page is about web pages and does not mention Mail.
• Desktop mail apps. None of the pages we read says what Outlook, Gmail in a browser or Apple Mail on a Mac does with a tel: link. The result likely depends on what the computer has set up to handle phone links, so click it on your own machine.
• Android. Google’s Android developer page on common intents is the right place, but the phone section did not load in the tool we used, so we make no claim.

Put plainly: a tel: link is a safe bet on a phone and an open question on a laptop. Readers who open the message on a phone can use it, so it is still worth adding. Keep the number visible as text as well, so a reader on a desktop can still read it and dial it from a handset. If your signature is long on phones, see mobile email signatures.

What about WhatsApp links?

WhatsApp has its own link form for starting a chat, different from tel:. WhatsApp’s click to chat help page would not load in our reading tool, so we have not restated its rules here. Read the page itself before you build one. Our separate article on a WhatsApp number in an email signature walks through the link, and our phone number in email signature guide covers how many numbers to show.

How emailfooter handles it

For a clickable phone number in email signature layouts, emailfooter builds the link from what the employee types in the phone field. In its engine, the link address keeps only digits and the plus sign, so +44 20 7946 0377 becomes tel:+442079460377. The catch follows from the rule: if someone types 020 7946 0377, the link is tel:02079460377, which has no country code. Ask staff to enter the international form.

Here is a drawn example. The number in this layout is a link:

Aligned layout. The company and person are made up.

emailfooter is English-only for now, has no click analytics, and does not push signatures into mailboxes. Employees follow the steps for their own mail app.

When the clickable phone number in email signature does not work

1. Nothing happens when tapped. The app may strip links in the signature, or the signature was pasted as plain text. Check whether the link survived by long-pressing it.
2. It dials a wrong or partial number. The link has no country code, or an extra zero.
3. Spaces break the link. Remove them from the address, and leave them in the visible text.
4. The number looks like a link on some phones but not others. Apple’s page says Safari on iOS detects telephone numbers by default, so a phone may style a plain number by itself. That is not necessarily your link.
5. Desktop click does nothing. The computer has no app set for phone links.
6. An extension is in the link. Take it out and write it in the text.

Testing a clickable phone number in email signature blocks

1. Send a message to yourself and open it on an iPhone and an Android phone.
2. Tap the number and check it opens the dialer with the full international number.
3. Open the same message on a laptop and click the number.
4. Turn off images and check the number still reads as text.
5. Reply to the message and tap the number in the reply.

Write down the result per device. That list tells you more than any compatibility chart for a clickable phone number in email signature setups, because the answer depends on the reader’s phone and mail app.

Frequently asked questions

How do I add a clickable phone number in email signature text?

Select the number, use your app’s link tool, and enter tel: followed by the number in international format, such as tel:+442079460377.

Does a tel link work in Gmail and Outlook?

Their signature pages describe adding links but do not mention tel:, so test it. Apple’s page says iOS asks for confirmation before dialing a tel link on a web page; what Gmail or Outlook do with one is not on the pages we read.

Should a clickable phone number in email signature blocks include spaces?

Not in the link. RFC 3966 says spaces are not allowed in URIs. Keep them in the visible text if you like.

Can I make a click to call email signature for an extension?

Link the main number and write the extension as text. Apple says a # or * in a tel URL stops the Phone app from dialing.