1) Name of person to whom you are talking
2) His/her employee number. This helps identify who you have talked to when you get moved up the food chain.
3) His/her extention number in case you forget something and want to talk to him/her again
4) Date and time of call
This provides a paper trail of your own of who you have talked to. Of course, for the item in question you have to decide if all of this is worth it.