Telephone equipment in Server Room

I have a client who want to put the telephone equipment in the server room. He figures that since the IT guys will be responsible for it any way it will save time and space to put them in the same room.
I don’t like it. I don’t want the phone guys near my servers and I don’t think the phone Co will like my I.T. personel being so close to the telco equipment rack. I would love some feedback. Examples of situations where it was a problem would be great.

Thanks