The Scenario

You're in Lisbon, or Bangkok, or Buenos Aires. You need to call a US number — Chase to clear a card-not-present block, a US hotel reception, a clinic in Boston, your mother. The number on the other end is a normal landline or mobile, not a messaging app.

You have several options on your phone right now: roaming, your home carrier's "Wi-Fi calling" feature, WhatsApp (in case the person picks up), a VoIP app like Voxa. Which one actually works in this scenario, and at what cost?

This article compares the four real options as they behave in 2026.

Option A: Direct Dial via Roaming

Just put +1 in front of the number and call from your phone like normal.

What happens: Your home carrier connects the call using a roaming partner in the country you're in, then routes it to the US. You're billed at international rates from your home carrier's pricing, often plus a roaming surcharge for being abroad.

Typical cost:

  • From a UK contract roaming in Europe: £0.50–£1.50/min (often the same as if you were at home, under EU "Roam Like At Home" extensions in 2026)
  • From a UK contract roaming outside Europe: £2.00–£3.50/min, sometimes higher
  • From a US contract roaming abroad: $1.50–$3.50/min plus a per-day pass fee in some markets

Pros: Works without thinking. No app, no setup. Caller ID shows your real number.

Cons: The most expensive option, always. Roaming surcharges have been quietly increased every year despite the general direction of telecom prices.

Use when: You need to make a single short, urgent call, you don't have time to set up anything else, and money is no object.

Option B: Carrier "Wi-Fi Calling" Feature

Most modern smartphones support Wi-Fi calling. When enabled, the phone places calls over a Wi-Fi network using your home carrier's infrastructure rather than the local mobile network.

What happens: Your phone connects to your home carrier via an IPsec tunnel over the Wi-Fi network. The call is then handled exactly as if you were at home — including, crucially, billing.

Typical cost:

  • A US-domestic call billed as a domestic call regardless of your physical location (if you have a US carrier with this feature)
  • A UK-to-US international call billed at UK international rates — typically the same £0.40–£1.50/min as direct dial
  • No additional roaming surcharge — that's the main benefit of Wi-Fi calling

Pros: Caller ID shows your home number, which is useful for US institutions that don't accept international callbacks. Avoids roaming surcharges if your country charges them.

Cons: Per-minute international rates still apply if you're calling internationally (i.e. from a UK contract to a US number). Wi-Fi calling does not reduce the international portion of the call — only the roaming portion. Many people misunderstand this.

Use when: You have a US carrier and want to call US numbers from abroad as if you were home — this is its sweet spot.

Option C: WhatsApp / FaceTime / Signal

If the person you're calling has the same app installed and a network connection, you can call them app-to-app for free.

Typical cost: Zero, on either side. You both pay only for the data, which is negligible (about 0.5 MB/minute).

Pros: Genuinely free. HD audio. Works on any Wi-Fi or mobile data globally.

Cons: Only works app-to-app. Cannot reach a bank, a hotel, a doctor, a government agency, a hotline, a delivery driver, or anyone using a normal phone line. This is the single biggest limitation and the reason VoIP-to-PSTN exists.

Use when: You're calling a personal contact who already uses the app.

Option D: VoIP Service to a Phone Number (Voxa et al.)

Open a browser (or an app, depending on the provider), sign in, dial the US number directly. The call goes over your internet connection to the provider's media servers, which route it to a US carrier and onto the recipient's normal phone.

What happens technically: Your device uses WebRTC to capture audio, encrypts it with DTLS-SRTP, and streams it to the provider. The provider hands the call to a tier-1 voice carrier, which terminates it on the destination network in the US. From the recipient's perspective, it's an ordinary incoming phone call.

Typical cost:

  • Voxa: €0.02/min to mainland US and Canada, including mobile numbers and toll-free numbers. €0.15/min to Alaska. €0.24/min to Yukon Territory. Prepaid in €5 increments; no monthly fee.
  • Other VoIP providers: similar range, $0.01–$0.05/min for US calls.

Pros: Cheap by a factor of 30–100 over carrier dialling. Reaches any phone number, not just app users. Works on hotel Wi-Fi, café Wi-Fi, cellular data, anywhere with ~50 kbps available.

Cons: Requires an internet connection of any kind. Your caller ID is either the provider's number, a local number you've purchased, or nothing — many US institutions will accept any inbound call but a few are wary of unknown international numbers.

Use when: You're calling any US phone number that isn't app-installable. Especially good for: banks, hotels, businesses, government, healthcare, real-world contacts.

Side-by-Side: 10-Minute Call to a US Bank from Bangkok

A common situation — you're abroad and need to clear something with a US bank. Here's the actual cost of a 10-minute call:

  • Roaming from a UK mobile contract in Thailand: ~£25–£35
  • Wi-Fi calling from same UK mobile (on hotel Wi-Fi) to US number: ~£10–£15 (no roaming surcharge, but still UK international rate)
  • WhatsApp to the bank: Doesn't work, the bank isn't on WhatsApp
  • Voxa on hotel Wi-Fi to the bank: €0.20 (10 × €0.02)

The Voxa option in this scenario is roughly 100× cheaper than roaming and works on any internet connection in the hotel — even when the local cellular network is overloaded.

What About "International Calling Without Internet"?

Sometimes you genuinely have no internet — on a flight before Wi-Fi turns on, in a remote area, in a country where data is unreliable. In that scenario:

  • Roaming direct dial is your only option, at full price
  • Wi-Fi calling fails without a Wi-Fi network
  • VoIP fails without internet
  • WhatsApp fails without internet

Plan ahead. Keep a small credit balance on a VoIP service set up before you travel so you can call from the first café or hotel you land in. The roaming option is the emergency fallback, not the everyday choice.

The Practical Setup

For most travellers and expats in 2026, the right setup looks like this:

  1. Default messaging app (WhatsApp, Signal, iMessage) for personal calls — free, instant.
  2. A pay-as-you-go VoIP account (Voxa or similar) for everything that needs to reach a real phone number — bank, hotel, doctor, employer. Top up €10 once a year; the credit doesn't expire.
  3. Carrier roaming as fallback when you have no internet at all.

The headline rate to call any US number on a setup like this is two cents a minute. The cost of not setting it up is roughly two pounds a minute the moment you actually need to make a call.