Porting your US phone number before you move abroad: keep it for about $5/month
The short version. Your US mobile number is a financial lifeline — banks, brokerages, and the IRS send SMS 2FA codes to it and quietly reject foreign and VoIP numbers. You can only move (“port”) a number while it’s still active; once it deactivates, it’s gone for good. So before you leave, port it to a cheap real-carrier MVNO like Tello (from $5/month) that keeps voice and text coming over Wi-Fi anywhere. Do this while you still have a US address and can call US support during business hours. Waiting until after you land is the expensive mistake.
I researched this closely for my own move from the US to Japan, and it’s the one loose end I keep telling people not to leave. Here’s the reasoning, the exact steps, and what it costs if you get it wrong.
Why the number itself is worth keeping
The number is not about staying reachable for friends. It’s about access to your money. In my case, my US bank accounts and brokerage are all tied to my personal US number — without SMS verification on that number, I’d lose that access entirely. That’s the whole reason I plan to carry my number to Japan rather than let it die.
Here’s what a US number is silently attached to:
- SMS 2FA at US institutions. Chase, Fidelity, most major banks and brokerages, plus the IRS and SSA, use SMS one-time codes and often will not deliver them to a foreign number.
- Account recovery. Password resets, “confirm it’s you” prompts, locked-account unlocks — all route to the number on file.
- Venmo, Zelle, contacts. These are keyed to your mobile number; lose it and they break without warning.
A related trap: VoIP numbers don’t count. Google Voice, TextNow, and Skype numbers show up as VoIP in carrier lookup databases, and banks like Chase silently reject them for 2FA. A real MVNO number (Tello runs on T-Mobile’s network) appears as a legitimate mobile number and passes those filters. I go deeper on that split in Google Voice vs. a real US number for 2FA — the short answer is a free VoIP line is fine for logging into Netflix and useless for logging into your bank.
What breaks if you wait until after you leave
This is the part nobody spells out. You cannot port a dead number. Porting is a transfer from an active line. The sequence that ruins people looks like this:
- You leave the US, figuring you’ll sort the phone out later.
- Your US credit card on the carrier account expires or gets cancelled.
- The carrier auto-cancels your plan for non-payment.
- The number is released back into the pool — permanently unrecoverable.
Now every account secured by that number needs a manual, cross-border identity-recovery process, done from Japan, across a 13–14 hour time difference, on hold with a US call center. Some of it you can fix; some accounts you may simply lose access to for weeks. Compare that to $5/month to keep the line alive. The math isn’t close.
The porting steps (do this before departure)
Porting a wireless number to another wireless carrier is your legal right under FCC number-portability rules. In practice, wireless-to-wireless ports typically complete same-day — though it’s worth noting that the FCC’s one-business-day completion mandate under 47 CFR § 52.35 technically applies only to simple wireline-to-wireline and intermodal (wireline↔wireless) ports, not wireless-to-wireless transfers. Carriers cannot refuse to port an active number in good standing, but there is no regulatory deadline binding them to same-day completion for wireless-to-wireless moves — fast turnaround is the norm, not a legal guarantee.
What you need before you start:
| Item | Where to get it |
|---|---|
| Current account number | Carrier app / bill |
| Transfer (port-out) PIN | Dial the code below |
| US billing ZIP code | Your current address |
| Account active + in good standing | Don’t cancel anything yet |
Getting your transfer PIN (as of 2026):
| Carrier | How | Note |
|---|---|---|
| Verizon | Dial #PORT from the phone | — |
| AT&T | Dial *PORT | PIN texted; needs account passcode |
| T-Mobile | Dial #PORT# | 6-digit PIN, valid 7 days only |
The one rule that matters most: do NOT cancel your old plan first. The number must still be active when the new carrier pulls it over. Start the port with the new carrier, wait for confirmation that it completed, then let the old line go. Cancel first and you’ve thrown the number away.
A couple of practical notes: new carriers may want a US billing address for setup, so it’s far easier to do this while you’re still in the country. And Tello now supports eSIM, so there’s no physical SIM to ship — you can activate before you fly.
Cost comparison: the keep-options
| Option | Monthly cost | Type | Banks accept 2FA? | Notes |
|---|---|---|---|---|
| Tello $5 plan | $5/mo | Real MVNO (T-Mobile) | Yes | ~100 min + unlimited text, no data; Wi-Fi calling |
| Tello $8 plan | $8/mo | Real MVNO (T-Mobile) | Yes | Unlimited talk + text, no data |
| Red Pocket annual | ~$5/mo ($60/yr prepaid) | Real MVNO (AT&T/T-Mobile/Verizon) | Yes | 12-month prepay; lets you pick the AT&T or Verizon network |
| US Mobile | ~$5–10/mo | Real MVNO | Yes | Flexible, slightly higher floor |
| Google Voice | Free | VoIP | Often no | Blocked by Chase et al.; fine for non-bank 2FA |
| TextNow | Free | VoIP | Often no | Same VoIP problem |
For a number you’re keeping purely as a 2FA and recovery lifeline, the $5 tier is the sweet spot: it’s a real mobile number, and SMS and calls arrive over any Wi-Fi connection abroad at no extra cost. My wife runs on Tello in the US — she’s on a ~$30 unlimited plan because she actually uses data — and it just works. For a keep-alive line abroad you don’t need data at all, which is how the price drops to $5.
(Full disclosure: the Tello links here are a referral — you and I each get $10 in Tello credit if you sign up through them. I’d flag Tello either way; it’s the plan my own family uses.)
Decision guide
- If your US bank, brokerage, or IRS logins use SMS 2FA on your number → port to a real MVNO before you leave. Most US persons do. My accounts are all tied to my number, so for me this isn’t optional.
- If you’ll keep using US brokerage or credit accounts from Japan → definitely keep the number, because those logins will demand it for years. See keeping your US brokerage when moving to Japan and keeping US credit cards after moving to Japan.
- If the number only secures non-financial logins (streaming, social) → a free VoIP line like Google Voice is fine. Don’t pay for something you don’t need.
- If you’ve already left and the line is still active → port it today, before the next unpaid bill kills it.
- If the number is already deactivated → it’s gone. Focus on updating every account to a new kept number and setting up an authenticator app where possible.
For the after-you’ve-left angle and how to actually receive codes day to day, I wrote a companion piece on keeping a US number for 2FA after leaving.
This is my own research and lived experience, not tax, legal, or investment advice — confirm plan details directly at the carrier’s site (Tello’s build-your-own pricing can shift) and check your bank’s own 2FA rules before you rely on any of it.
FAQ
Can I port my number after I’ve already moved to Japan?
Only if the line is still active. Porting transfers a live number to a new carrier, so as long as you haven’t let the old plan lapse, you can start the port from abroad — though troubleshooting across time zones is harder. Once the number deactivates for non-payment, it’s released permanently and cannot be recovered.
Will a Tello number actually receive my bank’s 2FA codes abroad?
Yes. Tello numbers are provisioned from T-Mobile’s network and appear as real mobile numbers, not VoIP, in the carrier databases banks check — so institutions that block Google Voice pass Tello through. With Wi-Fi calling enabled, the SMS codes and calls arrive over any Wi-Fi connection, which is how it works from Japan at no extra charge.
How much does keeping a US number really cost per year?
On Tello’s $5 plan, about $60/year — the tier gives you roughly 100 minutes and unlimited text with no data, which is all a keep-alive 2FA line needs. Red Pocket’s annual plans work out to a similar ~$60/year if you prepay 12 months — the draw there is that you can put the number on the AT&T or Verizon network instead. Either way it’s a rounding error next to the cost of being locked out of a US bank account from overseas.