correct sentence

[sumagraju]

Can you please correct the following sentence
I have been trying to reach Raj through phone, in vain

[MrPedantic]

Hello Suma, welcome to UsingEnglish!

I'll underline the part of the sentence that is incorrect:

1. I have been trying to reach Raj through phone, in vain.

Have a look at this Google search, and see if you can work out which preposition you should use:

??? the phone

If you post your answer, I'll check it for you later.

Bye,
MrP