Using Google Fi for a relatively private phone service

Created 2015-Aug-24
Updated 2016-Apr-19

In this post I’ll discuss ways to leverage the new Google Fi service in ways that are possibly more secure or more private when juxtaposed to regular AT&T, Verizon, Sprint, or T-Mobile phone service. Good planning and good practices can help people who are sensitive to physical location data sharing avert certain kinds of passive surveillance and in turn may prevent future active surveillance. While this information may be useful, it is not intended to solve your specific needs. You are ultimately responsible for understanding why you are performing these actions and non-actions.

Regarding SS7 attacks, the common way for such attacks to work requires that an attacker know your real cell phone number. Google Voice numbers are not vulnerable to these attacks. The same could be said for a landline phone number or any VoiP number like Skype.

Regular, long-term cell service wrongs:

  1. Requires government issued ID, which basically means connecting your government issued identity to a SIM card and other hardware identifiers.
  2. Requests (and at times requires) a Social Security Number, which also, basically, means connecting your government ID to hardware IDs.
  3. Requests the availability of voicemail, a service that is remotely accessible and is unlockable by a simple 4-digit pin code.
  4. Does not support two-factor authentication for access to sensitive account information.
  • Google Fi does not ask for identification, period. It is also possible to use prepaid credit/debit cards. As of April 2016, the Google/LG Nexus 5X is the cheapest phone, and you can buy it online or from a local retailer. Related notes: AT&T locks the SIM, so you can’t use an AT&T Google Nexus until AT&T (or a third party service) gives you a SIM unlock code. T-Mobile does not lock the SIM.
  • Voicemail is also an option with Fi. Fi support has stated that “Once you have set up your voicemail with Project Fi, it is impossible to turn off your voicemail,” and, “It will not be turned on until you activate it.” However, I presume that once Fi voicemail is activated, it is remotely accessible like regular voicemail service. If you perform the below steps, you will have no use for Fi Network voicemail, so don’t activate it.

Steps

The following configuration utilizes Google’s Hangout Dialer app that you will install and leverage on your Google Fi Nexus. The Hangouts Dialer will be able to make and receive all calls and texts using a Google Voice phone number. Two Google accounts are needed.

If your personal Google account has Google Voice presently, you will be forced to either give up that number or make it your Google Fi phone number. Either way, you will lose Google Voice functionality completely and is why a second Google account is needed.

  1. Register for Google Fi service using Google account #1 including ordering a new Nexus 6, 5X, or 6P.
  2. Do not share your Fi Network phone number. With anyone. Not your friends, family, or any services. Period.
  3. With Google account #2, register a Google Voice phone number.
  4. Download Google’s Hangouts Dialer. Google account #1 will automatically log in. Log in with Google account #2 (the Google Voice account). Then sign out from Google account #1 — only sign out in the Hangouts Dialer app, not from the Nexus completely.
  5. Configure Hangouts Dialer as follows: Settings > Enable merged conversations (yes), > account2@gmail.com > Incoming phone calls (yes), Messages (yes), > Customize invites > People who have your phone number (can contact you directly).
  6. Give out your Google Voice number to friends, family, and services. Calls and plain SMS will come through in the Hangouts Dialer app.
  7. Always make calls with the Hangouts Dialer app so the receiver’s caller ID shows your Google Voice number. It is best to remove the regular phone dialer app from the Android system tray and replace it with Hangouts Dialer.
  8. Added security

    1. Employ Google Authenticator two-factor authentication (2FA) for both accounts as soon as possible for better security. Avoid SMS 2FA because of the inherent vulnerabilities.
    2. Download Signal onto the Nexus and register your Google Voice phone number in Signal. While Signal will open up showing the real Google Fi phone number, delete it and enter the Google Voice number. The SMS verification will fail, so wait for the 2 minute countdown to expire then click “call me” for automated voice verification.
    3. Through the Google Voice web interface, optionally create a voicemail greeting that requests people to install and call back with Signal. Enabling “do not disturb” will enhance this goal because then nobody can call you and can only leave voicemails.
    4. If you haven’t already, talk to your friends and family about our need for privacy and security and inform them about Signal.

    Added anonymity

    The following are added steps in case you wish to also have probable anonymity to the service providers, in this case, Google, Sprint, and T-Mobile:

    1. If anonymity from the cellular provider is your goal, you’ll need to use cash to buy a Nexus 6, 5X, or 6P from a local retail location with cash and a prepaid debit card for monthly service. If you go this route, you will still need to order a Fi Sim Kit from Google with Google account #1 and have it shipped to you. If anonymity is your goal, consider renting an AirBnB or a hotel room using a pre-paid debit card and alias during the window of delivery.
    2. During registration for Google Fi service, account registration will require a “service address”. Use the above mentioned AirBnB address or be creative. You can always change the service address at a later date. All billing is electronic.
    3. You can consider not using your Nexus phone in any anchor points, including home or work. To do this, you would need to keep the device turned off at all times except when out and about. This makes it harder for service providers to identify you, but keep in mind that Google, Sprint, and T-Mobile can see network metadata and they can always record your voice when not using Signal. It’s still a tracking device with a microphone and camera!
    4. Consider removing the microphone and camera.

    Creating Google accounts

    Use an Android to create one or more Google accounts (Settings > Accounts > Add account > Google). Creating new Google accounts this way does not require the creator to enter in an existing email or phone number. Creating new Google accounts while using Tor will result in an account auto-lock. However, once an account is setup with two-factor authentication, you can log in via Tor Browser or Tails elsewhere. If you are trying to stay anonymous to Google, you’ll have to use a new Android (device IDs never before used by your real identity) and turn it on at a location far from any of your anchor points. Keep in mind that Google will know where your Fi device is when using the Fi network, but depending on your preparation/operational security, will not know the identity of the user.

    In retrospect

    Google, in addition to sporadic use of Sprint and T-Mobile network infrastructure, will be the only ones who know the identity (phone number and hardware IDs) of the subscriber. But you have much better control over defining the data and information that is linkable to this service.

    1. Adversaries can’t “ping” your cell phone if they can’t determine what your phone number is. However, if they run around your house with an IMSI catcher, it will not be hard for them to determine what number you’re using for service. It’s good practice to activate airplane mode when you enter into your home neighborhood, especially if your friends and family predominantly use Open Whisper Systems apps (Signal).
    2. Remote adversaries can’t track your physical location via possible SS7 vulnerabilities if they don’t know your real phone number.
    3. Network adversaries (telecommunication corporations or federal/local governments) can still inject or monitor your activity to “better service you” (sell your data to advertising networks), but unless they can connect that activity to a known identifier, you, personally aren’t vulnerable to said forms of surveillance.
    4. Network adversaries may employ voice recording and recognition technologies. The employment of said technology will only increase since it is a biomarker that financial institutions have started using for account verification purposes. If network adversaries are using this technology, there is no way to hide a real phone number or hardware device IDs from them unless you step up your paranoia and use a voice changer. Using Signal (end-to-end encryption) will mitigate only the voice print vulnerability. You will always divulge your hardware device IDs to a cellular network when using cell service.
    5. Endpoint adversaries (medical offices, food services, financial services, friends with or without Signal, etc) may also employ voice recording and recognition technologies. If you make calls using your Voice number (caller ID) to endpoint services, doing so will make it hard or impossible for a third party to link your personal ID to hardware ID.