Whether you go the sultry "really meet Jenny" angle or just try to find something that piques the interest of the average drunk male that would call, just to see what they're being referred to, you'd probably get enough takers to turn a tidy profit regardless of how crappy the ultimate toll line was. I doubt it takes all that much to convince callers that are already drunk and trying to do something they think is mildly funny already.
I think you should utilize a similar technology for your phone numbers.
Been listening to RBCP (The guy who does Snow Plow Show and Phone Losers of America) for a long time now. Great to throw on in the background for some laughs at the end of the day while reading.
Assuming that Jenny was 21 when the song was written, (since there is a chance the number was written on a bar's bathroom wall) she would be at least 62 years old now.
Statistically, there's at least a 1 in 4 chance that Jenny is dead now, and there is no chance that she didn't change her number after receiving 800 million horny crank calls.
Probably so he could rhyme 'mine' with 'nine'
8 dit-dit-dit-dit-dit-dit-dit-dit 6 dit-dit-dit-dit-dit-dit 7 dit-dit-dit-dit-dit....
ON the other hand, touch tones were invented in the 60's, so it's possible that they had access to the tech to touch dial at that time.