STUN is used to overcome NAT issues that can occur on some network environments, particularly sites with many phones and entry grade routers supplied by ISP's.
In addition to enabling STUN on handsets inside your network, it is important to ensure your router has SIP ALG disabled.
Press the OK button on the Yealink device. Locate the address listed in the IPv4 section.
Type the IPv4 address into your web browser to access the web-interface. Making sure that your PC is on the same network range as your handset.
Locate the login details of you handset and enter them into the login page, if the handset has been purchased via your customer portal then the details would have been emailed during the order process.
On the account tab of the Yealink web portal, change NAT to STUN and click Confirm.
Next on the network tab at the top select NAT.
Configure the STUN settings and click confirm. After clicking confirm, your phone will reset and STUN is enabled.
STUN Server: stun.voipcloud.online
STUN Port: 3478
You should now be able to make and receive calls without any one way audio issues. Should any further help be require please contact our support department.