The first telephones in India were witnessed in the year 1851.

Explanation:
The introduction of telephones in India was a significant milestone in the development of communication technology in the country. Here is a detailed explanation of the events leading to the first telephones in India:

1. Early Telecommunication in India:
- Prior to the introduction of telephones, telecommunication in India was mainly limited to the use of telegraphy. The first experimental telegraph line was established between Calcutta (now Kolkata) and Diamond Harbour in 1850.

2. Introduction of Telephones in India:
- The first telephones in India were introduced in 1851 by a British engineer named William O'Shaughnessy. He set up a telegraph line between Calcutta and Diamond Harbour and also demonstrated the transmission of sound through electrical wires.

3. Early Telephone Experiments:
- After the initial demonstration, further experiments and improvements were carried out by various individuals to develop the telephone technology in India. Prominent among them was Rao Bahadur Sakharam Ganesh Pandit, who conducted successful experiments with telephones in 1882.

4. Establishment of Telephone Exchanges:
- The first official telephone exchange in India was established in 1882 in the city of Bombay (now Mumbai). It was set up by the Bombay Telephone Company Limited, which later became the Indian Telephone Company.

5. Expansion and Development:
- With the establishment of telephone exchanges, the telecommunication network in India started to expand rapidly. By the early 20th century, major cities like Calcutta, Madras (now Chennai), and Delhi had their own telephone exchanges.

6. Nationalization and Growth:
- The telecommunication sector in India underwent significant changes in the post-independence era. In 1947, the Indian government nationalized all foreign telecommunication companies, leading to the formation of the Indian Posts and Telegraphs Department.
- Subsequently, the Department of Telecommunications was established in 1985, which was later corporatized to form Bharat Sanchar Nigam Limited (BSNL) in 2000.

In conclusion, the first telephones in India were witnessed in the year 1851. The introduction of telephones revolutionized communication in the country, leading to the establishment of telephone exchanges and the subsequent growth of the telecommunication sector.