Mexico City, September. One phone, one GeSIM plan, no backup SIM. Thirty days.

Here's the honest account.

What worked without friction

Data. Fast, consistent, never dropped. We were on Telcel's network for most of the trip, occasionally roaming to AT&T Mexico in the south. No configuration required. The VPN stayed on throughout without measurable speed impact.

Messaging. Signal, WhatsApp, Telegram — all fine. These apps verify numbers once and then use end-to-end encryption over data. After the initial virtual number verification, the carrier is irrelevant.

Navigation. Maps, transit apps, offline downloads — no issues. These don't need a phone number.

Crypto. Every wallet and exchange app we use works fine on a mobile data connection. Some required 2FA via the GeSIM virtual number — this worked as expected.

What required workarounds

Uber and Didi. Both initially rejected the US virtual number for account creation. The fix: use the virtual number for initial verification, then set a VOIP number as the recovery option. After the first trip, neither app ever called the number again.

Airbnb. Required a phone number that accepted SMS. Virtual number worked for this — no issues.

Local restaurant reservations via WhatsApp. No issues. WhatsApp number sharing doesn't surface the carrier.

What actually broke

One bank app triggered a fraud hold. The combination of a US virtual number, a Mexican IP (even through VPN), and an unusual login pattern triggered a manual review. Resolved with a customer service call from a different number. This is a real friction point for people who rely on mobile banking during travel.

Certain government services required a locally-registered number. We couldn't use these services during the trip. For most travelers, this isn't a blocker — but it's worth knowing in advance.

One carrier SMS verification (a local service in Oaxaca) explicitly rejected VoIP/virtual numbers. This is increasingly common with services that use carrier-level number classification APIs.

The net verdict

For privacy-focused travelers who understand the trade-offs, GeSIM works well for a 30-day trip. The friction points are predictable and manageable. The privacy gains — no identity registration, no carrier data trail, encrypted traffic — are real.

For someone who needs full banking and government service access from a foreign SIM, this isn't the right tool yet. We're working on it.