I call sometimes. I have also worked on a hotline taking night calls. They ask for a name. They don't care if its a real one or not they just need to fill in their log of in coming calls - time of call, name repeat caller Y N and description of call.
They listen and talk with the person until they are ready to hang up. Sometimes an emergency comes up where someone gets an active suicidal caller and then they may have to hang up with a person who they know is not active and just needed to talk for a few minutes.
Nothing is going to happen as long as you are not in the process of the suicidal act.
If you are in active suicidal state which is you have made the decision and are in the process. In which case they have caller ID so even before they answer your call they already know the area code and phone number you are calling from. They look on their list of area codes and see what district has that code and they allert that areas emergency services that they have an active suicidal from their area on the line. they give the caller ID information to that areas emergency services and while they keep the person on the line the emergency services are talking to the phone company to get exact location of the home, pay phone or cell phone that the call is coming from.
I didn't realize cell phones can be used to locate people until fairly recently when a person in this area was lost and the local emergeny services (police and so on) were able to use the relay towers to pinpoint the persons whereabouts once they had the phone number. they use a triangle system of which "towers" are being used to relay the call. once they have the three towers they have a real good idea of the area within a mile to a few miles.
Anyway back on track as long as you call before you are in active suicidal state all thats going to happen is like sitting down with your therapist and talking. The only difference is that its not face to face and the person answering the calls is usually a vollunteer not a certified or licensed therapist but if needed they have an on call certified and or licensed professional just a beeper away.
And no they don't tell your therapist unless of course your therapy agency is the the people running that hotline. then the info about the call will get forwarded to your therapist to be talked over with you to make sure you are ok and to have the paper put into your file the therapy agency keeps on you.