This messaging application known as iGap has the feature of creating username that has an interesting quality. If you create a username or an ID in iGap, you will be able to be caught by your friends and be added to their friends list just through searching your username in iGap without having any phone number of yours.
To tap the three lines icon at the top-right corner of the mobile screen and choose “Setting”, your account information will be open in which you can see “Username” option that has been filled with some letters and digits by default.
If you want to choose your favorite username or ID, just tap the field, type your ideal, and save it finally.
Now you have your own username that your friends can search and add you to their friend list through it with no need to have your number.