26 September

If your phone number is saved in someone else's contacts, their LINE app may add you as a friend automatically, because apps find friends by checking the numbers in your contacts against their servers. On 26 September 2017, Signal published a new way to do this matching without its servers seeing what is in your contacts. In the same post, Signal explained that uploading hashed phone numbers does not protect them, since the number of possible phone numbers is so small that the hashes can almost always be reversed. In February 2024 Signal added a setting that stops people from finding you by your number, and its Android beta in September 2026 lets you register without a phone number at all (see Phone-number-free registration in the Signal Android beta). On LINE, you can stop people who know your number from adding you by turning off the setting under Settings > Friends that allows others to add you.