Absolutely horrible. I was contacted by the recruiter via phone call. There were 2 things that were not right, the network quality of the call and the attitude of the recruiter. Her voice was so much muffled that I had difficulty in understanding her and when I requested her to repeat something, I was given and answer that "you should move to a better network area". Still putting up with that I continued the call and again when it impossible to understand what she was saying, I again requested her and was given the answer "do you understand English?" and not to forget "I told you to go to a better network area, what is wrong with you". And after a minute more she cut the call abruptly.
This is not just some daily chore that you will dump and try again another time. It is about the possible future of a candidate so maybe you should take it more seriously.
To that recruiter, yes I can understand English very well and I am not hard of hearing, the problem is your attitude.