I got an email lead saying that the guy in the recording is Ernie Anderson - and it definitely sounds like him. He did the "ABC Sunday Night Movie" stuff. So I am relatively confident that, at least the initial chain of profanity laden outtakes is from him, if not the whole thing.
In doing more searches about the New York Telephone clip in specific, the name of Rod Serling came up - he's the guy who does the talking bit at the start of The Twilight Zone.

It also sounds like him, although I'm leaning more toward that it is Ernie Anderson since it fits w/ the "ABC Sunday Night Movie" bit, and I found an outtake clip from him that sounded very similar. I haven't found any sort of things like that for Rod Sterling, but still wanted to note the above info I found.Fake New York Telephone Commercial
A parody of a New York Telephone commercial from the 1970's by Rod Serling (of Twilight Zone fame). This commercial explains how to get rid of prank callers in a not so nice matter. Funny but contains a few words you wouldn't want young children to hear.
The history of this commercial (as supplied by "BL" in February 2008):
I still have one of the original cassette tapes from the day Rod Serling made the recording. I have only recently converted it to digital and was wondering when it would show up on the Internet. There were only about 10 copies made and the originals cuts were destroyed.
Background: New York Tel had a very sophisticated audio and video studio at 1095 Avenue of the Americas in midtown Manhattan. Mr. Serling was recording several commercials for NYT at the time (about 1973-74). He was having a problem with one of the takes and he kept cracking up. It seems that Mr. Serling, the coiner of the phrase "you can't argue with a sick mind, so don't try", did indeed have a sick mind.
He revealed that every time he did a take, these other words would roll around in his head asking to come out. He asked that he just be permitted to get them out of his system so he could carry on with the rest of the takes. In humble awe the creator and chief writer of the Twilight Zone was let loose to speak his mind. What you hear in this recording is Rod Serling, getting the recording demons out of his system.
He was one of the nicest people you would ever want to meet. Charm, grace, a very sick sense of humor, and he always bought the coffee and, cigarettes.
Source: Anonymous Submission
So does anyone know more definitively about the original source of that bit?