The KX-TGEA20 handset comes with several Panasonic cordless phone models, including the KX-TGE24 systems. With the phone system in standby (no calls in or out, including intercom or calls to the paired cell phone), Press the right arrow button and press the right soft key (below the LCD screen) to open the Menu. Use the Up/Down arrows to navigate to Group. Press the soft key for Select. Use the Up/Down arrows to select a specific group and press the soft key for Select. Use the arrow keys to find the Group Ringer Tone option and press the soft key for Select. Use the Up/Down arrows to pick a ringer tone and press the soft key to Save the setting. Press Off to exit the menu system. Alternatively, press Menu as needed to return to the Group menu and choose a new group to edit that ringer tone setting.
The information on setting a ring tone per group is shown on page 25 of the manual available from the product page: https://shop.panasonic.com/cordless-corded-telephones/cordless-telephones/KX-TGE240B.html?t=reviews
. The current link to the manual is http://help.panasonic.ca/viewing/ALL/KX-TGE210/OI/TGE210_PNQX6358YA/TGE210_PNQX6358YA.pdf
I hope this helps.
(Note: the group ringer tone will only work when you have subscribed to the Caller ID feature with your telephone company.)