It is Sunnah (the practice of the Prophet) for men to recite it loudly and for women to recite it softly.
For Umrah, recitation stops upon seeing the Kaaba or starting the Tawaf. For Hajj, it typically continues until the first pebble is thrown at the Jamarat on the 10th of Dhul-Hijjah. Telbiye - Umre/Hac - Balcok Lebbeyk Allahumme Lebbeyk Telbiye Duasi Hac Duasi
"Buyur Allah’ım buyur! Emrindeyim buyur! Senin hiçbir ortağın yoktur. Emrindeyim buyur! Şüphesiz hamd sana mahsustur. Nimet de mülk de senindir. Senin hiçbir ortağın yoktur". It is Sunnah (the practice of the Prophet)
It is seen as a response to the eternal invitation sent by Prophet Ibrahim to all of humanity to perform pilgrimage. Lebbeyk Allahumme Lebbeyk Telbiye Duasi Hac Duasi