Skype for Business - Unable to communicate with personal skype

Issue:

We have set our Skype for Business to allow communications with personal Skype users, however we are still unable to do so.

Analysis:

A

To test your setup, you need a contact on Skype who's not behind your company firewall. They can be signed in to Skype using a Gmail account, Outlook.com account, or other type of email account.

1. After you change your external communications settings, WAIT UP TO 24 HOURS TO TEST.
2. Sign out of Skype for Business and then sign in again so you see the option to search the Skype Directory.
3. In Skype for Business, search for your contact in Skype, and send a request to chat.
   If you get the message it couldn't be sent due to company policy, you need to double-check your firewall settings.
4. Another way to test whether the problem is your firewall is to go to a wifi location not behind your firewall such as a coffee shop, and use Skype for Business to send a request to your Skype contact to chat.
• If you sent your Skype contact a request and they never received it, ask them to send you a request to chat. If the problem was establishing a connection between Skype and Skype for Business, that often solves it.
• Now if the message goes through at the coffee shop but not when you're at work, then you know the problem is your firewall.
  References: https://docs.microsoft.com/en-us/skypeforbusiness/set-up-skype-for-business-online/let-skype-for-business-users-add-skype-contacts
  
  If you sent your Skype contact a request and they never receive it, ask them to send you a request to chat. In these instances, that often establishes the connection. This is a known issue.
  
  References: https://support.office.com/en-us/article/add-a-contact-in-skype-for-business-89338023-2adf-4f5c-90b6-f8b6f72fadd1