The built-in phone directory on a Yealink T19P is is capable of storing up to 1000 contacts and 5 groups (including the default groups: Company, Family and Friend) in your phone's local directory.
How to add a group to the local directory
With the phone displaying the Idle screen, press the Dir soft key
Then press the AddGrp soft key
Enter the desired group name in the NAME field
Press or to select the desired group ring tone from the RING TONES field. If auto is selected, the group will use the ring tone assigned to the phone.
When you have finished, press the ADD soft key or if you want to exit the add group menu without saving the changes, press the BACK soft key.