Sayyidah Aisha (may Allah be pleased with her) said: When the Messenger of Allah (peace and blessings be upon him) would perform two rak'ahs before Fajr, if there was any need, he would speak to me, otherwise, without speaking, he would proceed for the prayer.
Hadith Referenceسنن دارمي / من كتاب الصللاة / 1484
From this hadith, it is established that in case of necessity, it is permissible to speak after performing the Sunnah prayers and before the congregational prayer. Furthermore, it is also evident that the Sunnah prayers of Fajr were performed by the Messenger of Allah (sallallahu alayhi wa sallam) in his home.