This is a model of phone that might best fit seniors. With a battery capacity of 1000 mAh you can make quite a few phone calls before the battery dies.
From Amazon
Maxcom Classic MK241 UK Sim Free 4G GSM Mobile Smart Phone with 2.4 Inch Colour Screen - Black
Viking Direct
maxcom Classic MK2414G VoWiFi VoLTE 4 GB 5 MP main camera, 0.3 MP front camera 8.1 cm 3.2 Inch Mobile Phone Black