I was voluntary inpatient once before. My Therapist at the time brought up the idea and I thought it sounded like I could have my own time to help figure out what was wrong with my brain, and that being there would be beneficial to me overall. I was able to be released when I wanted to be released after 3 weeks even though I still felt pretty bad overall. I mainly just wanted to get back to my normal life because I was just a 15 year old high school student at the time of my inpatient stay.
I think you can choose to call any mental hospital you want to, mine was just a 15 minute drive away from my house and that was the only one that my Therapist has called, and they accepted me.
Looking back on it, I do not have any useful coping mechanisms that I learned during my inpatient stay. Nothing came out of it that I can think of that I would call useful, BUT it is good because you have a guaranteed meeting with a Psychiatrist, instead of having to wait months for an appointment. I'm currently in college and there is a visiting Psychiatrist so I am lucky that I get to meet with her at a certain time and don't have to worry about waiting forever for an appointment.
Overall I think voluntary was better than if someone had forced me to go. I know my college wants to put me in there just because I said that I think about death all of the time, so I refrain from telling them my true feelings out of fear that they force me into a mental hospital.
I wish you the best of luck, hope you feel better.