Someone is using my phone number to make spam call

This is a longstanding issue known as 'call spoofing'. While there's unfortunately no way to fully prevent spoofing, there are steps you can take. The first would be to change the call security settings on your phone to restrict outgoing calls to just your phone's contacts (there are different methods to do this based on the specific device you use). You can also mention it in a new voicemail message to let callers know, or change your number. Admittedly, that's not the optimal choice but it should stop the issue associated with your current one. Of course as always, also be careful where you share your number online, as data breaches are a big cause of these scenarios.