Skype requires that Ports 80 and 443 be open for outgoing Transmission Control Protocol (TCP) transmissions and recommends that all destination ports above 1024 also remain open.
In addition, Ports 5060 and 8000 should remain open for incoming and outgoing UDP transmissions.
Skype prefers UDP for voice transmissions.
What protocols does Skype for business use?
For Skype to work correctly, the following ports need to be open in your firewall:
Is Skype TCP or UDP?
In addition, Skype uses TCP for call signalling, and both UDP and TCP for transporting media traffic. Moreover, Skype uses 256-bit AES (Advanced Encryption Standard) encryption and 1024 bit RSA to negotiate symmetric AES keys.
How does Skype operate?
When you sign on to Skype, your computer becomes one node in a global network of equal peers. Each Skype user runs a piece of software called a client that allows them to send messages to other Skype users, make calls, send files, and play real-time games.
Does Skype use SIP?
But along with SIP, there are a number of other signaling protocols used for voice and video communication on IP networks. Although Skype does offer SIP functions, you will want to try some other service and client for SIP, since what Skype proposes is paid and intended for businesses.