Your Travel eSIM Won't Give You a US Phone Number

Write your real foreign number with the full country code (e.g. +44 7...) on any US form that asks for a phone number — most don’t actually require a US number, they just assume one. That workaround exists because most travel eSIMs hand you mobile data with no dialable number or SMS capability, which isn’t obvious until you’re staring at a government form that assumes otherwise.

Data-only means no number

Most of the popular travel eSIMs (Airalo, Holafly, and similar providers) are data-only. You get mobile internet in the US, but no dialable phone number and no SMS capability. There’s nothing wrong with your eSIM; it’s simply not built to hand you a US phone number the way a physical local SIM card would.

This becomes a real, practical problem the moment a US form assumes everyone filling it out has a normal US mobile number to receive a callback or a text verification code.

What to put on the form instead

Two workable options, depending on what the form requires:

1. Use your real foreign phone number, with the country code included. Most US government forms don’t require the number to be a US number; they just want a way to reach you. Writing it out with the full international country code (e.g., +44 7... for a UK number) is normally accepted.

2. Lean on email as your primary contact wherever the form allows it. For the Colorado SOS apostille process specifically, this is the more reliable path: the Authentications office already works by email for its free pre-submission document review, so email is a channel they’re set up to use anyway.

Whether a given form treats "phone number" as a strictly required field or an optional one can vary. If a specific Colorado form won't accept a foreign-format number, email the relevant office directly and ask how they'd like international applicants without a US number to proceed.

The broader lesson

If you’re planning a Colorado elopement from abroad, don’t assume “I have an eSIM with data” is the same as “I have a US phone number.” For anything that specifically requires a callback or SMS (as opposed to just internet access for maps, email, and browsing), you’ll want either your real foreign number ready to hand over in international format, or a plan to route everything through email instead. Given that the SOS office already operates by email for document review, building your paperwork trail around email from the start will save you a few awkward form fields later.