Your question stumps me a bit, I would imagine God/Universe, but I don't think anyone truly knows the answer. I do know that when we are intently speaking (in the mind) such as in a prayer or meditation, a guide can hear it, as it is our intent.

The existence of something other than what we can see in the physical allows the possibility for there to be communication in a myriad of ways. I have heard that we are not in the body, on the other side, we can communicate telepathically. It’s who you direct the communication that hears it in that case.

Thank you for the question!