The dial string is `+1` followed by the 10-digit US number (area code + subscriber number). Many US toll-free prefixes (`800`, `888`, `877`, `866`, `855`, `844`) fail or misroute from the UK. For the IRS and Social Security, use the published international numbers, not the domestic 1-800 lines printed on letters.

The dial string

To call the US from the UK:

›`+1 {area code} {number}`, or
›`00 1 {area code} {number}` from a UK landline.

There is no leading zero to drop on standard US numbers. A New York number printed as `(212) 555-0142` becomes `+1 212 555 0142`. A Los Angeles number `(310) 555-0199` becomes `+1 310 555 0199`.

Mobile vs landline

US mobiles and landlines share the same 10-digit NANP format. You cannot reliably tell mobile from landline by looking at the number. Area codes are three digits; major examples include New York `212`/`646`/`917`, Los Angeles `310`/`424`, Chicago `312`/`773`, Houston `713`, Miami `305`/`786`.

The US does not bill the receiver for ordinary incoming international calls.

What it costs

Four realistic routes for a UK→US call in 2026:

›UK mobile international add-on. EE’s International Pass and similar Vodafone/O2 bundles cover many US destinations more cheaply than raw pay-as-you-go; without a pass, EE Zone pricing for the US has historically been measured in pounds per minute on standard tariffs (check the current EE price guide before relying on pay-as-you-go).
›Pre-paid international calling card. Low headline rates to US landlines; connection fees punish short IVR calls.
›VoIP app-to-phone. Teams Phone and Viber Out terminate to US numbers at low single-digit US cents per minute on many routes.
›Browser-to-phone via WorldDial. From $0.02/min to US destinations on the public [rates](/rates) table, see [call the USA](/call-usa) for country context.

For holds longer than about 10 minutes on IRS or bank IVRs, per-minute browser or VoIP routes beat UK carrier pay-as-you-go unless a cheap US-inclusive pass is already active.

Toll-free numbers from this corridor

US `800`/`888`/`877`/`866`/`855`/`844` numbers are provisioned for North American origination. From the UK many return “not available from your location” or ring forever. Use the geographic or international line the institution publishes:

›IRS International Taxpayer Service: `+1 267-941-1000` ([IRS international contact](https://www.irs.gov/help/contact-my-local-office-internationally); also summarised on [IRS from abroad](/call-irs-from-abroad))
›SSA Office of International Operations: `+1 855-522-6936` ([SSA foreign directory](https://www.ssa.gov/foreign/foreign.htm))

Best calling windows

US Eastern is UTC-5 (winter) or UTC-4 (EDT). The UK is 5 hours ahead in winter and 4 hours ahead in summer.

Best window for US government and bank helplines: `09:00-11:00 US Eastern` (shortest morning queues). That is `14:00-16:00 UK time` in winter or `13:00-15:00 UK time` in summer.

Avoid Monday mornings US Eastern and the day after US federal holidays, queues double. IRS international hours run early (from 06:00 ET); that maps to late morning UK time and is often the shortest wait.

Pitfalls specific to this corridor

›Domestic 1-800 on benefit letters. SSA’s `1-800-772-1213` and IRS `1-800-829-1040` are the most common wasted UK→US dials. The letter rarely prints the international alternative next to the bold toll-free headline, dig for the “outside the United States” paragraph on the agency site before redialing.
›NANP confusion with Canada and the Caribbean. `+1` also serves Canada and several Caribbean territories. Confirm the area code is US before assuming US rates, hours, and holiday closures.
›DTMF on tax and bank IVRs. US agency menus are deep; some softphone routes deliver touch-tones poorly. If the menu restarts after every keypress, switch route or device before investing in a long hold.
›Hold music drops on weak Wi-Fi. A 40-60 minute IRS hold fails if the laptop sleeps or the network roams between SSIDs. Plug in power, disable sleep, and prefer a wired or stable 5 GHz link for anything expected to exceed 15 minutes.
›US federal holidays vs UK bank holidays. The calendars do not match. A quiet UK Monday can still be a US holiday with skeleton staffing, check the US federal holiday list before committing an early morning to a queue.

Quick checklist

›Dial `+1` plus ten digits; do not add a UK-style leading `0`.
›Replace failed US toll-free numbers with the published international/geographic line.
›Aim for `09:00-11:00` US Eastern when possible.
›Have SSN/ITIN, account numbers, and notice IDs ready.
›Prefer a per-minute route unless a UK international pass already covers the US cheaply.

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FAQs

What is the international dialing code for the United States?

`+1`. From the UK dial `+1` or `00 1`, then the 10-digit number. See also [US calling codes](/en/calling-codes/usa).

Can I dial US 800 toll-free numbers from the UK?

Often no. Many US toll-free numbers reject international originations. Use the institution’s geographic or international number instead.

What's the cheapest way to call the US from the UK?

A UK international pass that includes the US can win for short calls. For long IVR holds, browser-to-phone from about $0.02/min usually beats standard UK mobile pay-as-you-go. Check [rates](/rates). UK-side dialing basics are on [call the UK](/call-uk).

Will WhatsApp work for this call?

Only for people who use WhatsApp. US federal agencies and most bank fraud lines do not accept WhatsApp for account authentication.

How to call the US from the United Kingdom in 2026