Cannot call some Outlook contacts from within Skype

I'm trying to call an Outlook contact which shows up in Skype but it never works for this contact. I can call other Outlook contacts from within Skype with no problems.

Why doesn't it work for some contacts?

In order for the Skype calling function to work with Outlook contacts, you must specify the international phone number of that contact in Outlook. This means that not only must you specify the area code, you must also specify the land code as well.

Skype accepts phone numbers in the following format;

  • International format with a + or 00
    +123456789
    00123456789
  • With and without spaces
    +1 23456789
    +1 234 56789
  • With enclosed area code
    +1 (234) 56789
  • With additional 0 in enclosed area code
    +1 (0234) 56789
    +1 (0)234 56789
  • Other formatting characters than spaces
    +1-234-56789
    +1-234/56789
    +1.234.56789

Note 1: To handle all of the above number formats correctly, you’ll require at least Skype 3.6.

Note 2: Currently Skype (at least for version 5.6 and previous) cannot properly handle phone numbers which have extensions. Instead, it will dial the number, including the extension, in one go. This usually will result in either not being able to connect at all or needing to specify the extension manually via the number pad in Skype after the initial connection has been established.