Talbiyah 

It is obligatory to say the Labbayk during Ihram with correct Arabic accent and it should be as follows:

لَبَّيْكَ اللَّهُمَّ لَبَّيْكَ، لَبَّيْكَ لاَ شَرِيْكَ لَكَ لَبَّيْكَ، إِنَّ الْحَمْدَ وَالنِّعْمَةَ لَكَ وَالْمُلْكَ لاَشَرِيْكَ لَكَ

“Labbayk, Allahumma labbayk, labbayka la sharika laka labbayk, Innal Hamda wan nimata laka wal mulk, la sharika lak.”

(Here I am, O Lord, here I am, you indeed have no partner, here I am. No Doubt, all praise and bounties are yours, and so is the absolute Domain. You indeed have no partners, here I am)

It is obligatory to say Labbayk during Ihram only once but sunnah is to recite it thrice. After that it is Mustahab to repeat that in different conditions as much as possible. E.g. while getting in and leaving a car, passing low and high lands, after awakening and after prayers. Men should recite Labbayk with a loud voice, while women should recite it in low voice.