Signal uses your existing phone number so there are no separate logins or usernames to manage or lose. Your phone number can be your
- Mobile device number
- Google Voice number
- Any VoIP number
- Landline number
- All Signal messaging and calling that you send or receive will display the number you registered Signal iOS with.
See also the support page on verification for iOS.
If you are using a phone number that is not your mobile device or SIM card number, then please read the following for what phone number your message or call will originate from.
- If you send a Signal message, it is private and originates from your Google Voice number as that is your Signal registered number. Your recipient will see your Signal registered number which is your Google Voice number.
- If you send an insecure SMS/MMS, it originates from you mobile SIM card phone number as it is going through your mobile plan and will reveal your mobile number to your recipient.
- If you enable Google Voice SMS forwarding, then you can respond to insecure SMS/MMS messages linked to your Google Voice number, it will go through your mobile plan and Google and it will show your Google Voice number to your recipient.
- If you place a Signal call, it is private and originates from your Signal registered number and is going through the internet.
- If you place an insecure call, it originates from you mobile SIM card phone number and goes through your mobile plan.
See also the support page on verification for Android.