How to Call The UK from The US: Dialing Format, Area Codes and Caller ID Rules

A London number written as 020 7946 0123 becomes 011 44 20 7946 0123 from a US phone. That one pattern covers UK landlines, mobiles and most business numbers. This guide covers the details that trip callers up: which area code to use, when the time gap shrinks to four hours, and why calls from US sales teams sometimes never ring in the UK.

How do you call the UK from the US?

Calling the UK from the US takes four steps: dial 011, dial 44, drop the UK number's leading 0, then dial the rest. The sequence is the same from a landline, a mobile or a softphone, which is calling software that runs on a computer or phone.

1. Dial 011. This is the US international exit code, which tells your carrier the call is leaving North America.
2. Dial 44. This is the country code for the United Kingdom, covering England, Scotland, Wales and Northern Ireland.
3. Drop the leading 0 from the UK number. UK numbers are written with a 0 for calls inside the country. Keeping it after 44 is the most common reason a US-to-UK call fails. (Most failed calls go wrong here)
4. Dial the remaining digits. Enter the rest of the number exactly as written, usually 10 digits.

On a smartphone, a plus sign can replace 011. Hold the 0 key until + appears, then dial 44 and the number: +44 20 7946 0123. Saving UK contacts in this +44 format means they work from any country.

How do you dial UK landlines, mobiles and freephone numbers?

Every UK number type uses the same 011 44 prefix: London landlines continue with 20, other landlines with a three-digit code such as 161, mobiles with 7, and freephone lines with 808. The table shows how each type is written in the UK and how to dial it from a US phone.

UK number types and how to dial them from the US (example numbers from Ofcom's drama ranges)

Calling a UK mobile from the US

UK mobile numbers start with 07, so from the US they start with 011 44 7. Many US rate cards price UK mobiles higher than UK landlines, so check both rates if you call mobiles often.

Calling UK freephone and 03 numbers from abroad

UK freephone numbers (0800 and 0808) are free only for callers inside the UK, and many don't accept international calls at all. Numbers starting 03 are national-rate lines that UK businesses and public bodies use instead of a city code. If an 0800 number won't connect, look on the company's website for a +44 landline or 03 alternative.

What are the main UK area codes?

  A UK area code is the 2 to 5 digits after the leading 0 that identify a city or town, and larger cities have shorter codes: London is 020, Birmingham 0121, Manchester 0161. The table lists ten major cities. Ofcom's area code lookup covers every other town. 

Area codes for major UK cities

What time is it in the UK compared with the US?

The UK is 5 hours ahead of US Eastern Time for most of the year. UK clocks run on Greenwich Mean Time (GMT) in winter and British Summer Time (BST, one hour ahead of GMT) in summer.

Usual time difference between the UK and US time zones

The overlap with a UK working day is short. A UK office open 9am to 5pm can be reached from New York between 4am and noon Eastern, and from Los Angeles only between 1am and 9am Pacific.

When does the UK and US time difference change?

  The UK and US time difference shrinks by one hour twice a year because the two countries change clocks on different Sundays. UK clocks go back on the last Sunday in October and forward on the last Sunday in March, according to GOV.UK. US clocks change on the second Sunday in March and the first Sunday in November.

As of October 2026, the next two windows when London is 4 hours ahead of New York instead of 5 are:

• Oct 25 – 31 2026: UK clocks go back a week before US clocks.
• Mar 14 – 27 2027: US clocks go forward two weeks before UK clocks.

Put both dates in your calendar before booking calls with UK contacts.

How much does it cost to call the UK from the US?

The cost of calling the UK from the US depends on your provider and whether you dial a landline or a mobile, and there are four ways to pay: carrier per-minute rates, an international add-on, an internet calling app, or a business phone system. Rates change often, so check your provider's current international rate page before a long call.

These are the main ways to pay for UK calls:

• Carrier per-minute rates Most US mobile and landline plans bill UK calls per minute unless international calling is included.
• International add-ons Verizon, AT&T and T-Mobile each sell international calling add-ons that lower the rate for frequent callers.
• Internet calling apps WhatsApp and FaceTime Audio calls are free over Wi-Fi or data when both people use the app.
• Business phone systems VoIP and cloud phone systems bill international minutes to the company and log each call.

Why do business calls from the US to the UK get blocked?

  Business calls from the US to the UK get blocked when they display a UK caller ID that UK networks cannot verify. Ofcom, the UK communications regulator, has tightened its rules on calls from abroad that show UK numbers, because scammers use them to look local.

Three rule changes matter for US teams:

• Before 2025 UK providers already had to block calls from abroad that use a UK number as the Network Number, which identifies where a call comes from.
• January 29, 2025 UK providers must block calls from abroad that falsely display a UK landline number as the Presentation Number, the caller ID the recipient sees, except in limited legitimate cases.
• July 15, 2026 Ofcom's strengthened guidance says providers should withhold the caller ID of calls that appear to come from a UK mobile roaming abroad, unless they can verify it.

A US rep who shows a borrowed UK 020 number through a cheap international route risks the call being dropped before it rings. Calls showing a UK mobile number may arrive as "Withheld", which many people ignore.

The safer choice is your real US number. Otherwise, use a UK number assigned to your business and carried by a provider that can verify it.

What rules apply to sales calls from the US to UK numbers?

  Sales calls to UK numbers are covered by the Privacy and Electronic Communications Regulations (PECR), the UK rules on marketing by phone, email and text. The Information Commissioner's Office (ICO), the UK data protection regulator, enforces them, and the ICO's telephone marketing guidance sets out what callers must do before marketing to UK numbers.

Before making marketing calls to the UK, the guidance expects callers to:

• Screen consumer numbers against the Telephone Preference Service (TPS), the UK's opt-out register for live sales calls.

• Screen business numbers against both the TPS and the Corporate TPS (CTPS), the register for corporate lines, because sole traders register on the TPS.

• Keep an internal do-not-call list and honor every opt-out.

• Display a number the person can call back, and say who is calling.

• Get specific consent before any automated call that plays a recorded message.

The ICO notes that this guidance is under review after the Data (Use and Access) Act, so recheck it before launching a UK campaign.

How can a US team call UK customers at scale?

The right setup for calling UK customers depends on volume: occasional callers need a phone plan, while teams calling the UK daily need UK numbers and campaign controls.

• Choose an international add-onif you make a few UK calls a month.
• Choose an internet calling appif the person you're calling already uses the same app.
• Choose a cloud phone system with UK numbersif a team calls UK prospects or customers every day and needs call logs, recordings and compliance controls.

  HyperDial fits the third case. HyperDial's UK phone numbers include geographic ranges such as 020 and 0161, 0800 freephone and 03 national ranges. Proof of address, which Ofcom requires for geographic numbers, is collected during setup, and number porting is coordinated with your current carrier.

  The HyperDial power dialer places calls from records in Salesforce, HubSpot or Zoho and logs each one automatically. Calling windows and abandoned-call limits are set per campaign, and recording announcements can be configured for consent, as described on the HyperDial security and compliance page. 

Limits to know: the UK numbers page does not list UK mobile (07) numbers, so ask before ordering if your campaign needs one. If your agents sit in the US, ask how your UK caller ID will be presented before your first campaign.