If your phone number appears as unknown when making calls, it may be because:
• There is a restriction due to the recipient’s device or carrier
Your caller ID depends on the recipient’s device. For some device models, your name will appear as it's registered in the device's contacts list. On other devices, your phone number may appear in an international format or as an unknown number.
Also, if the mobile service provider of the person you're calling has caller ID spoofing countermeasures in place, your phone number will appear as unknown or private, even if you've verified your number to allow others to see it.
Note: To find out if a mobile service provider is implementing caller ID spoofing countermeasures, we ask that you contact them directly.
• You didn't verify your phone number
If you don’t see a phone number at the top of the screen after going to the Friends or More tab > Settings > LINE Out, it means that your phone number hasn't been verified and will appear as unknown.
For help with verifying your phone number, see the following Help article: