Similar to interviewing.io, Pramp is another site that pairs interviewees together for practice phone interviews with a shared document to type in. It also lets you play the role of interviewer for half the session which is a good experience.
This is exactly what you are looking for. Good luck.
I'm in the same state, got many calls from Google interviewers. I am a little slow in coding hard problems on codeforces. Another couple of months n I shd be good
https://www.pramp.com