Signal requests permissions to enable certain features, such as sharing a photo or displaying your contacts. You can verify how these permissions are used by looking through the source code. Signal is fully open source and always will be. The code has been audited both by third-party security firms and individual researchers. This is one of many reasons that we are committed to Open Source; it helps to ensure that careful scrutiny is possible.
Android
To manage permissions on phones running Android 6.0 or later:
• Go to Android phone Settings app > Apps & Notifications (depending on your device, this may look different) > Signal > App Permissions (depending on your device, this may look different) > Turn permissions on.
Permissions Requested
Identity
• find accounts on the device - Allows Signal to find accounts and to check for Signal contacts. These accounts can be viewed in the Accounts section of your Android System Settings.
• read your own contact card - Access to your contact cards allows Signal to associate your phone number with your name.
• modify your own contact card - Signal can add new phone numbers to existing contacts and create brand new contacts as well.
Calendar
• read calendar events plus confidential information - See below.
• add or modify calendar events and send email to guests without owners' knowledge - Calendar permissions will allow you to share your calendar events in messages to your friends.
Contacts
• find accounts on the device - Allows Signal to find accounts and to check for Signal contacts. These accounts can be viewed in the Accounts section of your Android System Settings.
• read your contacts - Access to your contacts lets Signal associate incoming phone numbers with names and display contact information when you are selecting who to compose a message to.
• modify your contacts - Signal can add new phone numbers to existing contacts and create brand new contacts as well.
Location
• approximate location (network-based) - See below.
• precise location (GPS and network-based) - Allows you to share your current location in messages with your friends.
SMS
• read your text messages (SMS or MMS) - See below.
• receive text messages (MMS) - See below.
• receive text messages (SMS) - See below.
• send SMS messages - See below.
• edit your text messages (SMS or MMS) - Signal is capable of functioning as a complete replacement to your phone’s stock messaging application. In order to do this, it needs to be able to send and receive text messages (both SMS and MMS). You can also import your existing SMS messages into Signal when it is first installed, and these permissions allow that database to be read as well.
Phone
• directly call phone numbers - See below.
• reroute outgoing calls - Allows call handling for both insecure and private calls.
• read call log - This functionality is used to display a list of recently used contacts when you are composing a new message from a share action.
• read phone status and identity - Allows Signal to determine your phone number and Device ID. These are used to register for Signal.
Photos/Media/Files
• read the contents of your USB storage - See below.
• modify or delete the contents of your USB storage - Signal stores its encrypted database on your phone. When you receive an incoming picture, video, or audio message, these are also stored locally on your phone. These permissions are necessary to enable backup functionality.
Storage
• read the contents of your USB storage - See below.
• modify or delete the contents of your USB storage - Signal stores its encrypted database on your phone. When you receive an incoming picture, video, or audio message, these are also stored locally on your phone. These permissions are necessary to enable backup functionality.
Camera
• take pictures and videos - Signal includes a direct capture feature where you can take a picture within the app and quickly send it in a message. This permission is necessary for calls.
Microphone
• record audio - Allows you to be heard on voice and video calls, and to record voice notes.
Wi-Fi connection information
• view Wi-Fi connections - Required in order to receive SMS, MMS, and Signal messages under various network conditions (e.g. 3G, WiFi, LTE, etc.). Signal messages are sent and received over the internet and do not use traditional SMS/MMS. This also allows Signal to determine when services are not available. For example, MMS sent over T-Mobile requires a cellular connection without WiFi, and Signal handles this case itself.
Device ID & call information
• read phone status and identity - Allows Signal to determine your phone number and Device ID. This is used to register for Signal.
Other
• send WAP-PUSH-received broadcast - This is used for SMS/MMS delivery receipts.
• receive data from internet - See below.
• view network connections - Required in order to receive SMS, MMS, and Signal messages under various network conditions (e.g. 3G, WiFi, LTE, etc.). Signal messages are sent and received over the internet, and do not use traditional SMS/MMS. This also allows Signal to determine when services are not available.
• create accounts and set passwords - Allows Signal to create an account on your device, viewable at System Settings > Accounts.
• pair with Bluetooth devices - Allows use of a Bluetooth connection while on a call.
• send sticky broadcast - This is so Signal can run reliably and smoothly with other apps on your phone. For example, if you have low battery then you can still receive messages, or if you are attaching an image then you are requesting access to a photograph on your device.
• change network connectivity - See below.
• connect and disconnect from Wi-Fi - Required in order to receive SMS, MMS, and Signal messages under various network conditions (e.g. 3G, WiFi, LTE, etc.). Signal messages are sent and received over the internet and do not use traditional SMS/MMS. This also allows Signal to determine when services are not available. For example, MMS sent over T-Mobile requires a cellular connection without WiFi, and Signal handles this case itself.
• disable your screen lock - Allows Signal to keep the phone unlocked while on a call.
• full network access - Required in order to receive SMS, MMS, and Signal messages under various network conditions (e.g. 3G, WiFi, LTE, etc.). Signal messages are sent and received over the internet and do not use traditional SMS/MMS. This also allows Signal to determine when services are not available.
• change your audio settings - Used for sound notifications.
• read sync settings - Allows the app to receive messages on time.
• run at startup - Enables Signal to handle the receipt of messages when the phone first starts up but before the user has launched Signal. Without this, there may be a delay in receiving messages.
• set wallpaper - Allows the app to set the wallpaper. For example, if someone sends you an image you can set it as wallpaper directly from Signal.
• use accounts on the device - Allows Signal to add an account on your device, viewable at System Settings > Accounts.
• control vibration - Used for vibrating notifications.
• prevent device from sleeping - Allows Signal to keep the phone active when it is performing certain tasks such as delivering or receiving a message.
• toggle sync on and off - This is used to make sure your contacts are up to date and is the standard way in modern Android to handle syncing, viewable at System Settings > Accounts.
iOS
To manage permissions on your iPhone:
- Go to
iPhone Settings > Signal
Permissions Requested
Notifications - Allows you to know when you've received a message or call.
- iPhone Settings > Signal > Notifications > Allow Notifications
- iPhone Settings > Notifications > Signal > Allow Notifications
Contacts - This lets you communicate with your contacts and display contact names.
- iPhone Settings > Signal > Allow Contacts
- iPhone Settings > Privacy > Contacts > Allow Signal
Photos - This enables the app to send pictures or videos that are already stored on your phone.
- iPhone Settings > Signal > Photos
- iPhone Settings > Privacy > Photos > Allow Photos
Microphone - This enables recording voice notes and allows you to be heard on voice and video calls.
- iPhone Settings > Signal > Microphone
- iPhone Settings > Privacy > Microphone > Allow Microphone
Camera - Required to place video calls and record pictures or video.
- iPhone Settings > Signal > Camera
- iPhone Settings > Privacy > Camera > Allow Camera
Background App Refresh - Allows Signal to receive messages and calls on time. Without this, there may be a delay in sending and receiving messages.
- iPhone Settings > Signal > Allow Background App Refresh
- iPhone Settings > General > Background App Refresh > Allow Background App Refresh AND scroll to Signal and Allow Signal
- Disable Low Power Mode (below)
Cellular Data - Allows Signal to receive messages and calls on time. Without this, there may be a delay in sending and receiving messages.
- iPhone Settings > Cellular > Allow Cellular Data
- iPhone Settings > Scroll down to Signal > Allow Cellular Data
Other iPhone Settings
Low Power Mode - This can interfere with the ability to receive messages and calls on time.
- iPhone Settings > Battery > Disable Low Power Mode
Restrictions - These restrictions can interfere with the ability to modify other permissions or receive messages and calls on time. Without this, there may be a delay in sending and receiving messages.
- iPhone Settings > General > Restrictions > Disable Restrictions
- iPhone Settings > General > Restrictions > If restricted, enable Camera, Contacts, Photos, Microphone, Cellular Data Use, Background App Refresh
- iPhone Settings > Screen Time > Always Allowed > Add Signal
Desktop
To manage permissions go to Signal Desktop preferences:
In Signal, tap your profile 
> 
Preferences... to view Signal settings.
Permissions Requested
Camera and microphone - This lets you send voice notes from your desktop. The camera will be used in the future to support video calling.