User busy signal

When I try to call someone with an iPhone it rings once and then pops up saying “user busy” without going to voicemail. Does this mean I’ve been blocked by that user? On my iPhone settings I’ve opted to not show my called ID so I thought this would mean my call would still go through so I’m not sure what’s creating the issue. A friend and I tested it where she blocked my number and when I called, my call went through and she answered. She said it showed as a restricted number though. Any advice on what’s causing the “user busy” signal if it’s not due to being blocked?

not sure how important to mention this is but it also looks like my iMessages are not being shown as “delivered” to this user, which I’m aware is an indication of being blocked.

thanks in advance.