Can 1 sim call displaying number then unknown?

[AC Question]

Can 1 sim call displaying number then unknown ?

Hi guys I'm a bit confused ...when a friend calls, sometimes their number that I have stored on my fone appears to let me know it's them who's calling..other times it's ' unknown ' ...my Question is :- with only 1 sim..is this possible...I know they own a nokia dual sim phone, they say they are using 1 sim..but when they call from ' unknown ' the cxn is better..and I don't understand why sometimes it displays their number and sometimes just says ' unknown ' ..any answers are much appreciated thanx in advance...

 

[B. Diddy]

Re: Can 1 sim call displaying number then unknown ?

Welcome to Android Central! Do you know if that person ever calls you using VOIP (e.g., calling using Hangouts Dialer instead of the main dialer)? Calls from Hangouts Dialer might come through as an Unknown number.

 

[Meriem123]

Re: Can 1 sim call displaying number then unknown ?

Thank you for responding to my question can you explain what that means sorry

 

[B. Diddy]

Re: Can 1 sim call displaying number then unknown ?

There are services that allow you to make calls from your phone using the internet (either wi-fi or 3G/4G mobile data), instead of your voice signal. This is referred to as VOIP (or Voice Over Internet Protocol). These kinds of calls are often free (at least within the US). Read more about Hangouts calls here: https://support.google.com/hangouts/answer/6079055?hl=en