Once you are brought to a point where you are in crisis and you are calling a hotline, you probably do not really want to have to wait for someone to be available. Unfortunately, a lot of these hotlines are run by volunteers and on donations so there is a limited number of people available to help which is often less than the amount of people who need help. I often recommend calling hotlines within your city so they have to respond to less people but it can still mean you may have to wait for the next available advocate. On this page, there are things you can do while you wait.
I know you have probably heard so many times, to just breathe but breathing helps calm your body physiologically even if your mind is racing.
Breathing in patterns gives you something to focus on. You can breath in for 5 and breath out for 3, or count your breath until you get to 127. It can give you something to focus on until they become available.
Often, the first thing they will ask when they respond on the hotline is what is going on. I find it helpful, especially when also dealing with anxiety, to prepare for this.
Write down what is happening and what you hope to talk to them about. And this can be in relation to many different things. If you need resources, often they can give them to you as well.
Look directly around you. And take note of every little thing in your environment. Every color, every object, every sound, every smell. If you are an artist, maybe even draw it. If you are a writer, write it as you would describe to someone who is not in the room. Fixate on every little detail to create a full picture of your environment.
Disclaimer: I am not a mental health professional. If you are in extreme crisis please call your local emergency services or your local suicide hotline. This site is a collection of research and resources to help you.