One repeats just as the muadhidhin(one who calls to prayer) says, except when he says:

حَيِّ عَلَى الصَّلَاةِ حَيِّ عَلَى الْفَلَاحِ

''Come to prayer, come to success''[HAYYA A''LA SWALAAH... HAYYA A''LA AL-FALAH...]
instead, one should say:

لَا حَوْلَ وَلَا قُوَّةَ إِلَّا بِاللَّهِ

Immediatly following the declaration of faith called by the muadhdhin, one says:

''And I too bear witness that none has the right to be worshipped except Allah, alone, without partner, and thatMuhammad is His slave and Messanger. I am pleased with Allah as a Lord, and Muhammad as a Messenger and Islam as a relegion.'' [Muslim 1/290]

أَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللَّهُ وَحْدَهُ لَا شَرِيكَ لَهُ وَأَشْهَدُ أَنَّ مُحَمَّدَاً عَبْدَهُ وَرَسُولَهُ وَأَشْهَدُ أَنَّ مُحَمَّدَاً عَبْدَهُ وَرَسُولَهُ رَضِيتُ بِاللَّهِ رَبَّاً وَبِمُحَمَّدٍ رَسُولَاً وَبِالْإِسْلَامِ دِينَاً

[WA ANA ASH-HADU AN-LA ILAAHA ILLA ALLAHU WAHADHU LA SHAEEKA LAHU WA ANNA MUHAMMADAN ABDUHU WA RASOOLUHU, RADHEETU BILLAHI RABBA, WA MUHAMMADIN RASOOLA WA BI ISLAAMI DEENAN]

اللَّهُمَّ رَبَّ هَذِهِ الدَّعْوَةِ التَّامَّةِ وَالصَّلَاةِ الْقَائِمَةِ آتِ مُحَمَّدَاً الْوَسِيلَةَ وَالْفَضِيلَةَ وَابْعَثْهُ مَقَامَاً مَحْمُودَاً الَّذِي وَعَدْتَهُ إِنَّكَ لَا تُخْلِفُ الْمِيعَادَ

'' O Allah, Owner of this perfect call and Owner of this prayer to be performed, bestow upon Muhammad al-waseelah[A station in paradise] and al-Fadeelah [A rank above the rest of the creation] and send him upon a praised platform [One in which all of creation will praise him on, in order to bring about the account quickly and be relived from the lengthy standing or the role of intercession] which You have promised him. Verily, You never fail in Your promise.'' [Al-Bukhari]

[ALLAHUMMA RABBA HADIHI DA''WATI TAAMMATI WAS-SALAATHIL QAAMATI AATI MUHAMMADAN WA-SEELATA WA-ALFADEELATA WA-BA''TH HU MAQAAMAN MAHMOODAN ALLADHEE WA-ADTAHU, INNAKA LA TUKHLIFUL MEEADI]