Reducing SPAM: Supplied ATA Better than SIP Credentials?

For minimizing SPAM calls, will using the supplied ATA be better than using SIP credentials on a BYOD?

I am in the process of porting two lines over from another VoIP provider, and I am getting a lot of SPAM on the first line with the old provider. I wanted to make sure my SPAM problem doesn't continue after the port is complete.

Some background: The caller ID shows up as three digit numbers. My first line at the old provider is set up with SIP credentials on UDP port 5060. As far as I could tell, it may be possible that bots have found me at that port number. I've changed the port number to see if that would help.

Tech support got back to me with this: "As for direct SIP scanning our ATA uses a non-standard SIP port (usually 5078/5079) which helps 'hide' the device from SIP scanning of normal SIP ports (5060). However, this can also usually be done within the BYOD itself. By adjusting the port on which it connects you can also have it use non-standard SIP ports like 5078/5079." So I should be OK now.