"They met me and to thanked that we have done it very quickly," Sinha said.
Vodafone CEO designate and Chief Financial Officer Nick Read, after meeting Sinha, had Tuesday confirmed receiving the letter approving the merger.
"We are happy to receive the letter," he had said.
There have been industry speculations that Idea Cellular and Vodafone may challenge in court the demand of Rs 39.76 billion for one time spectrum charge of Vodafone India, and joint bank guarantee of Rs 33.42 billion sought by DoT before it grants final approval for the merger.
Vodafone executives did not respond to queries over their plans to make payment and furnishing bank guarantee.
Vodafone CEO Vittorio Colao, who will remain in office till October, said: "Yes. I am optimistic" that the new entity, to be named Vodafone Idea Ltd, will be in place before he remits the office."
When asked for plans of the British telecom firm post the new entity comes in place, Read said: "We have always been a strong investor in India. We will remain that".
The combined operations of Idea and Vodafone will create the country's largest telecom operator worth over $23 billion (or over Rs 1.5 trillion), with a 35 per cent market share and a subscriber base of around 430 million.
Debt-ridden firms Idea and Vodafone India are in process of merging their businesses in India as it is expected to bring down cost of their operations and give them relief from cut-throat competition in the market where margins have hit rock bottom with free voice calls.
Vodafone Idea will have the capacity to provide 4G spectrum in all telecom circles of the country. According to a presentation by Idea, the combined 4G spectrum of both the companies is capable of offering up to 450 megabit per second broadband speed on mobile phones in 12 telecom areas in the country.
With the new entity coming in force, Bharti Airtel will lose the tag of India's biggest telecom service provider to the new entity. The combined debt of both the companies is estimated to be around Rs 1.15 trillion.
Vodafone will own 45.1 per cent stake in the combined entity, while Kumar Mangalam Birla-led Aditya Birla Group will hold 26 per cent and Idea, 28.9 per cent. The Aditya Birla Group has the right to acquire up to 9.5 per cent additional stake from Vodafone under an agreed mechanism with a view to equalising the shareholding over time.
Balesh Sharma will be the new CEO of the merged entity. Idea's chief financial officer Akshaya Moondra will head the financial operations of the new entity as its CFO. Ambrish Jain, currently the deputy MD at Idea Cellular, is set to become the new chief operating officer.