WARNING - UNBLURRED SPOILERS AHEAD
I’ve always had a bad feeling with this puzzle.
That’s because, before the last build, the two agents couldn’t talk each other.
The agent down there could see the graffiti with the name of the person to call in an emergency, but couldn’t communicate with the agent up there, the one who could check the phonebook.
So solving the puzzle is a matter of telepathy between the two agents!
I think that the puzzle could be made better now that the agents can have a dialogue through the manhole.
After the agent in the sewers sees the graffiti, a new dialogue line appears to communicate to the partner the name to look up the phonebook.
So when the agent comes back to the manhole he/she can reveal the number to call to the trapped partner. Or, if the agent up has a cell phone in its inventory, he/she can call for help directly.
To prevent a telepathic shortcut (the player solves the puzzle in the old fashion) the agent down the sewers could refuse to use the phone if he/she has not discovered the right number to call through dialogue with the partner.
Maybe he/she, when asked to use the public phone, could say something like “I don’t want to risk to waste my dime calling a random number”.
What do you think of this? I know it’s a bit complicated, but I have to confess that the telepathy puzzle always seemed awkward to me.