To borrow a term from the Friends and Family side of the forum, you have every right to set boundaries. For your friend, that boundary might be, "I will not carry on a phone conversation with someone who is drunk."
When I was still drinking, my best friend, who had left AA and resumed drinking, came to visit me. The level of his drinking was alarming and I was at a loss for what to do. Finally his moral lapses crossed the line of our friendship. I asked him to leave. He was welcome to return, but only if he was sober.
I never saw him again. He killed himself three months later.
I still wonder if I handled it wrong. But objectively, I'm sure I did the right thing.