Kala said to Radha, "who were you speaking to over the phone?"

In changing a direct speech sentence to indirect speech, it's important to understand the rules for reported speech, which include changes in pronouns, tense, and word order. In the given sentence, Kala asked Radha about a past event.

Here's how the conversion works:

The direct speech sentence is: "Kala said to Radha, 'who were you speaking to over the phone?'"

In indirect speech, you need to report what was said, which includes changes in tense and pronoun:

"who" becomes "who she"
"were" becomes "had been"

So, the correct transformation is: "Kala asked Radha who she had been speaking to over the phone."