Hi Shwetha,
Telephonic interview is also a mode of the selection process as you can judge a candidate's voice confidence, especially if you are looking into the ITES sector. Many companies generally conduct telephonic interviews as part of the preliminary selection.
First, let him/her know who you are. This will make them alert, and they can give their best. Ask them simple questions regarding their education and past experience. Don't delve too much into technical details as they don't need to form a proper sentence for it. However, we are looking to check their proficiency in English, so ask questions where they need to form a complete sentence.
You can even give them a topic and ask them to speak on it if you don't have any time constraints.
That's the input I can provide.
Regards,
Vishnu
You can reach me at vishnu.srikanth@lorventech.com