On your Yealink phone:
Press the ‘Dir’ softkey button.
Select item 1. Local Directory
Select item 1. Contacts
Enter the name of the contact or the 3 digit local extension number (use the ‘abc’ key to alternate keypad typing modes)
Press the down arrow button once
Enter the 7 digit local extension number (this number may be found at http://manage.press8.com and navigate to Features/Telephone Lines)
Press the down arrow button until you get to the ‘Ring’ page.
Press the right or left arrow key to change the ring tone. The tone will play after a 2 second pause.
Repeat this procedure for any other local extensions that you would like a distinctive ring tone.