This is the 11460th most frequent Russian word.
дозвонившейся
"Having successfully called (on the phone)."
The word 'дозвонившейся' is used in its past active participle form, denoting the one who successfully completed the action of calling through.
Моя сестра была единственной, дозвонившейся в радио-шоу.
My sister was the only one who managed to get through to the radio show.
The word 'дозвонившийся' is used as a verbal adjective describing the subjects who completed the action of calling through.
Каждый, дозвонившийся в течение часа, получил приз.
Everyone who got through within an hour received a prize.
Here, 'дозвонившаяся' describes the woman as having successfully completed the action of calling through to reach someone.