Another way to disarm gatekeepers is to name drop other people you have spoken to in the organization so that you don’t look like an outsider who is calling to try to work your way in. The way to do that is to say something like this:

I spoke with Tom Jones in accounting, and now I am trying to reach someone in HR. Do you know who the best person for me to connect with is?

By mentioning this, not only will the gatekeeper feel like you must be OK to let in because you are already somewhat on the inside, but he or she will feel like it will not be good to be rude or completely block you out because you appear to already have some existing relationships or business going on with the company.
If you like the logic with this tactic but you feel that you cannot use it because you have not spoken to anyone in the organization yet, you can modify your name-drop to use the names of people you are planning to meet with by saying something like this:

We are planning on meeting with Mary Smith next month, but we need to connect with an operations manager prior to that. Can you help point me in the right direction for who I should reach out to?

You can use this even if you don’t have meetings on the schedule because you
are saying that you are planning to meet and not that you have a meeting scheduled.