TL;DR: Yes, you can use your foreign phone number to set up a Portuguese chave digital. It just can’t be a VOIP number, like Google Voice.

I put off getting a chave digital for nearly two years, since I didn’t quite understand what I needed it for. Yes, you can use it to login to ePortugal, Portal das Finanças, and SNS Online. You can also login with your NIF. You use your chave digital to sign documents, sure, but I’ve made it this far without needing to sign anything digitally.

It was only when I decided to get rid of my Portuguese phone number that I realized I’d need a digital key. My accounts with Portuguese companies didn’t provide an option to update my phone number and everything had 2-factor authentication. A chave digital would mean I could still login even after changing my phone number.

Only your chave digital is connected to your phone number. Having it connected to my Portuguese number wouldn’t help, since the whole idea was to get rid of my Portuguese number. Could I get a chave digital connected to my US number? I asked in a certain infamous Facebook group. Or tired to ask, since my question was declined with a note: “If you are in Portugal, why don’t you have a Portuguese number?”

I suspected this wasn’t quite right. All Portuguese citizens are entitled to a chave digital and Portugal is the country in Western Europe with the largest number of citizens living abroad. I doubt all of them are paying for a Portuguese phone plan and paying roaming fees every time they need to login to a Portuguese website. More promisingly, I noticed the login field for the chave digital gives you the option to change the country code.

I went to the Loja Cascais, where an agent confirmed that it was no problem to use a foreign phone number for a chave digital.

Only…the SMS didn’t come through to my US number, which is a Google Voice number. Either chave digital doesn’t accept VOIP numbers or Google Voice is blocking the message because it’s automatically generated. Had I activated my Google Fi plan ahead of time, I could have given them that number and it would have worked.

For now, I came up with a workaround. And if something goes wrong, I know it’ll be easy to sort out by creating a new chave digital.

How to use your chave digital without your Portuguese phone service

If you have a chave digital with your Portuguese phone number and don’t have your Portuguese phone service activated or lose your number, you can still use your chave digital as long as you take these steps ahead of time.

The trick is to download the Autenticação app to your phone. You’ll need your Portuguese phone to set it up, using a SMS to verify your account during setup. After that, you’ll no longer need an SMS to login.

Once it’s set up, you can login to the Autenticação app with your biometrics and it will generate a code for you.

How to set up a chave digital with a foreign number in person

  1. Make sure your foreign phone service is activated and allows automatically generated SMS
  2. You can add your NIF, NISS and numero de utente, so have these handy
  3. Get your passport and your phone and go to a Loja Cidadão
  4. Pick up your sena and set up your digital key with an agent when your number is called

How to set up a chave digital with a foreign number online

  1. Make sure your foreign phone service is activated and allows automatically generated SMS
  2. Make sure you know your login credentials for the Portal das Finanças
  3. You can add your NIF, NISS and numero de utente, so have these handy
  4. Follow these instructions from Lisbob, providing your foreign number rather than your Portuguese number