Squirt bottle, I read somewhere that when puppies and dogs are chewing furniture or cables, anything, hide in somewhere where he will not see you and squirt a bit of water. If he keeps on chewing it, keep on squirting, this will get the puppy to think that he is being punished by the furniture, in this case, the cable from the telephone, unless of course, he loves water! LOL joking, try that and see what happens.
It's a pleasure to help you. You know i live somewhere near Brazil, in Chile, you know that country? but I can't speak portuguese of course!!!.
You know i used to do the same thing with my puppy, and in a result he quite enjoyed it, so he kept doing something bad, for something he liked. I think you should tell him a very loud NO! and may be raise your hand like you are going to hit him, that's what i do to my pup, and she stays quite quiet!