Originally Posted by Ali Safavi

Here is how you fix the issue on iPhone version of Skype app:

1- On Skype app go to the “Settings”
2- Scroll down and tap on option “Account and Profile”
3- Tap on “Your Profile”
4- Scroll down and tap on “Add Mobile Phone”
5- Add your cellphone number
6- Click on “Caller ID” check-box.
7- Click on “Verify”. Skype will send you a SMS with your verification code. Enter the code and complete verification.
8- You’re all set!
9- You’re welcome