Phone number in email signature: which to show and how to format it

A phone number in email signature text should be one number per purpose, written with a plus sign and a country code, and labelled so the reader knows whether it is an office line or a mobile. Which number you show depends on who is meant to answer it: the office line for a team, the direct line or mobile for a person that clients really call.

This page does two jobs. It gives a decision table for office, mobile, WhatsApp and extension numbers, and it shows how to write each kind for the US, Canada, the UK and four African countries. The sources we read in October 2026 are the GOV.UK style guide, RFC 3966 for phone links, and ITU’s E.164 page.

Which phone number in email signature to show: a decision table

Choosing a phone number in email signature text starts with who should be able to reach you. Then pick the row.

Number	Show it when	Leave it out when	Note
Office or company line	People reach you through a switchboard, or your firm wants one number on every message	Everyone has a direct line	The safe default for regulated and larger firms.
Direct line	Clients call you personally, and the line is answered	Calls go unanswered while you are in meetings	Put it first if you have it.
Mobile	You agree to be reached by phone or text, and the company allows it	You are an executive with an assistant, or the number is personal	Stays in old threads long after you change roles.
WhatsApp	You answer WhatsApp for work, and clients already use it	You only look at it now and then	Needs its own link; see the WhatsApp guide.
Extension	The switchboard is the only way in	A direct line exists	Awkward to link; see below.

The deciding question is whether a human will pick up. In our view, a number that rings out looks worse than no number, because the reader tried and failed. Our article on what to include rates the number for a solo worker, an employee and a regulated firm.

Mobile or office line?

The usual trade-off is reach against permanence. A mobile reaches you wherever you are, but the number goes with the person. An office line stays with the company. That is our reasoning, not a rule. A middle path is to show the office line on every message and add the mobile only for roles that need it, such as field staff or sales.

How to write a phone number in email signature text

Five rules. Where one rests on a source, the source is named; the rest are our own choices.

1. Start with a plus sign and the country code. RFC 3966, which defines the tel: link format, says globally unique numbers are identified by the leading plus sign. ITU’s E.164 page lists the international numbering plan as in force in its 02/26 edition.
2. Drop the leading zero you dial at home. A Nigerian 0802 000 0000 becomes +234 802 000 0000. The regulator sources behind this are in our guide to writing a phone number internationally, which we did not re-check for this page.
3. Group with single spaces. RFC 3966 allows hyphens, dots and brackets as visual separators and says they do not affect the call. Spaces are simply the quietest choice.
4. Label the number in words. The GOV.UK style guide says to use “Telephone:” or “Mobile phone:” and not abbreviations. In a signature, “Phone” and “Mobile” are plenty.
5. One format for everyone. Mixed styles make a company look unsorted. Decide once.

A word on brackets. The GOV.UK guide’s own example is +44 (0)29 2018 0542, with the zero in brackets, because it writes for readers who may dial from inside or outside the UK. In a signature that people tap on a phone, we leave the (0) out.

Phone number in email signature: the same rules for seven countries

The table shows how to write a phone number in email signature text for each, using made-up numbers. “At home” is the local style.

Country	At home	In a signature
United States	(415) 555 0173	+1 415 555 0173
Canada	(604) 555 0148	+1 604 555 0148
United Kingdom	07700 900456	+44 7700 900456
Nigeria	0803 555 0126	+234 803 555 0126
Kenya	0711 555 014	+254 711 555 014
South Africa	083 555 0129	+27 83 555 0129
Ghana	024 555 0127	+233 24 555 0127

The pattern is the same everywhere: plus sign, country code, then the national number without its leading zero. The US and Canada share the country code 1, so they look alike. Where the digits fall after the code depends on each country’s numbering plan, so check your own number rather than copying a row. The fuller table, with the regulator notes behind each country, is in the international format guide.

Making the phone number in email signature tappable

On a phone, a number that cannot be tapped is a small chore. The tap-to-call link is a tel: link, and the usual form uses the plus sign and digits only. RFC 3966 says visual separators are not used for placing a call, so the spaces you see do not have to be in the link.

emailfooter does this for you. Its source builds the link by stripping everything except digits and the plus sign, so +254 711 555 014 becomes tel:+254711555014 while the signature still shows the spaced form. It labels the company number “Phone” and the employee’s number “Mobile”. Test the result by tapping each number on a phone. Our clickable phone number guide has the detail.

Extensions and WhatsApp

Write an extension on the same line as the main number, after it: +1 415 555 0100 ext. 214. RFC 3966 gives the extension its own parameter in the link, written “;ext=” followed by digits. We have not tested how each phone handles it, so we cannot say every device will dial the extension.

There is a catch in emailfooter. Because its link keeps only digits and the plus sign, an extension typed into the phone field would be joined onto the number and dial a wrong one. If you use emailfooter, keep extensions out of the phone field and prefer a direct line.

A WhatsApp number is separate, since it opens a chat and not a call. Give it its own labelled line and link, even if it is the same number as the mobile.

One rule for the phone number in email signature across a team

Pick the rule once and write it down. In emailfooter the admin chooses whether the company number, each employee’s own number or both appear, and employees cannot override it. Employees still install the signature in their mail app by following the steps shown, because emailfooter does not push signatures into mailboxes.

This first example shows both numbers, labelled. The second shows an executive whose signature carries only the company line.

Both numbers, labelled Phone and Mobile, in the same international form. The company and person are made up.

Company line only, so the number stays valid when people change roles. The firm and person are made up.

Getting the phone number in email signature blocks right once is easier than correcting it later, because a signature travels inside forwarded messages and old threads for years. Check the number against your own phone, tap it, and then roll it out. The complete signature guide shows where it fits among the other parts.

Frequently asked questions

How to write phone number in email signature text?

Use a plus sign, the country code and the number without its leading zero, with single spaces. A Nigerian 0803 555 0126 becomes +234 803 555 0126.

Should I put my mobile number in my email signature?

Only if you are happy to be called or texted on it, and your employer allows it. Otherwise show the office line.

How many numbers should a phone number in email signature blocks include?

One per purpose, and no more than two. Label each one so the reader knows which to dial.

Can a phone number in email signature blocks be a WhatsApp number?

Yes, on its own labelled line with its own link. It opens a chat, so it should not share a line with the call number.

How do I write an extension in an email signature?

Put it after the main number, as “ext. 214”. Avoid extensions where you can by giving people a direct line.