When you install Skype to your computer, the application chooses at random a port number through which it funnels incoming data. The port communicates using both the transmission control protocol and user datagram protocol; Skype relies on a TCP connection when signing on to the Skype network and on a UDP connection when sending or receiving voice transmissions. If the audio quality of your voice calls is poor or degrades over time, you can create a rule in Windows Firewall or on your router to open the appropriate port and prevent the firewall from restricting incoming traffic over UDP.

Create a Rule in Windows Firewall

Step 1

Select "Options" from the Tools menu in Skype and then click the "Advanced" tab.

Step 2

Click "Connections" and then review the information in the right pane to see which port Skype uses for incoming connections.

Step 3

Press "Windows-W" to open the Settings pane, type "firewall" into the search field and then select "Windows Firewall" from the results.

Step 4

Choose "Advanced Settings" from the left to open Windows Firewall with Advanced Security, and then click "Inbound Rules."

Step 5

Select "New Rule" from the Actions pane, choose "Port" for the rule type and then click "Next."

Step 6

Set the protocol to "UDP." Enter the port number from Step 2 into the "Specific Local Ports" field and then click "Next."

Step 7

Click "Allow the Connection" and then click "Next." Choose from the options whether to allow the port on domain or a public or private network and then click "Next." For the best protection, only allow the connection on a private network.

Step 8

Enter "Skype" into the "Name" field, enter an optional description and then click "Finish" to allow UDP communication in Skype.

Create a Rule on Your Routing Device

Step 1

Select "Options" from the Tools menu in Skype and then click the "Advanced" tab.

Step 2

Click "Connections" and then review the information in the right pane to see which port Skype uses for incoming connections.

Step 3

Right-click the wireless network connection icon in the notification area and then choose "Open Network and Sharing Center" from the context menu.

Step 4

Select "Change Adapter Settings" from the left and then right-click "Wi-Fi." Choose "Status" from the context menu and then click the "Details" button.

Step 5

Write down the information displayed next to IPv4 Address and IPv4 Default Gateway. The former is the IP address of your computer, and the latter, the IP address of your router.

Step 6

Open a Web browser, type the IP address of your router into the address bar and then press "Enter" to access your router's Web-based configuration utility.

Step 7

Enter your administrative credentials into the fields provided, or log in to the device using the default credentials. You can find default credentials on the product label attached to the bottom or back of your router or in the product manual.

Step 8

Search the menu for an option such as "Port Forwarding," "Applications & Gaming" or "Virtual Servers."

Step 9

Click the appropriate menu option and then type "Skype" into the "Service Name," "Application Name," "Description" or similar field.

Step 10

Type the applicable port number into the "Inbound Port," "Internet Port" or similar field. If the router requires you to specify a port range or private port, enter the same number into both fields.

Step 11

Set the protocol to "UDP" or "Both" and then enter your IP address into the appropriate field.

Step 12

Check the "Enable" or "Enabled" option, if applicable, and then click the button to apply or save your changes.

Step 13

Close and then restart Skype for the changes to take effect.