Speaking during Tawaf is permissible and does not invalidate it. The Prophet (peace be upon him) said: 'Tawaf around the House is like prayer, except that Allah has permitted speaking in it. So whoever speaks in it, let him speak only good.' This hadith establishes that while talking is allowed, it should be purposeful and good speech rather than idle chatter.
The recommended practice during Tawaf is to engage in dhikr (remembrance of Allah), dua (supplication), istighfar (seeking forgiveness), and Quran recitation. You may supplicate in any language — Arabic is not required for personal duas. There are no specific mandatory duas assigned to each circuit, despite what some printed Tawaf dua booklets may suggest. Those circuit-specific duas are later compilations, not from the Prophet's practice. The only Sunnah-specific dua is between the Yamani corner and the Black Stone: 'Rabbana atina fi'd-dunya hasanah wa fi'l-akhirati hasanah wa qina adhab an-nar.'
Brief necessary conversation with companions — such as coordinating meeting points, checking on someone's well-being, or answering important questions — is fine. However, extended worldly discussions, arguments, gossiping, phone calls about business, and loud talking that disturbs others should be avoided. Use the precious time of Tawaf to connect with Allah through heartfelt supplication.