Can’t say hello when answering a phone call

Can’t say hello when answering a phone call Ever since I was a teenager I sometimes block when having to answer a phone call or introducing myself to a room full of people. It seems like whenever there is a time frame to speak I block. It feels like my throat is so tight and I can’t physically get my words out. The more I think about it the worse it gets! I just started a new job and sometimes I have to answer the phone with my colleagues near by listening and I am so scared Incase I block and can’t get my words out. I don’t know what to do. I can’t get it off my mind which is making it worse and I am feeling so down about it. Please help does anyone have the same problem and how to get over it. Thank you.