I think the silver lining of loneliness being so prevalent is that other people are feeling it too and want to do something about it. Knowing nothing about your situation I would guess that statistically if you're feeling lonely then your friends are also likely to feel lonely -- maybe they also say that their friends don't call them. I think this is a great opportunity in that there's desire from other people to connect with you that you could tap into.

Speaking from my own experience, it's very uncomfortable to be forward about trying to make friends / strengthen friendships. It reminds me of the stigma that online dating had when I first did it circa 2010 -- it has a connotation of being "desperate", and maybe that cool people wouldn't have to be desperate. But in my personal experience I've seen this shift a lot in the last year, where there is a lot of relief and appreciation when I mention wanting more friends and hint that I want to be friends with the person I'm talking to (they often respond by saying that they want more friends too). So I personally decided that I would rather risk looking desperate than feel lonely, and I recommend that tradeoff, especially because it's not perceived negatively like we worry it will be.

That's not to say that I think there's some easy option that I think you're avoiding; from my experience it has taken a number of incremental steps (and it's not like I've fully "solved" it). I guess I'm just trying to say don't get discouraged by the magnitude of the situation -- it might seem like a single phone call to a friend could never make a difference, but things like that add up over time.

As for practical suggestions, I've found video games to be a good activity to do with people that I don't live near. I've also found Buddhist meditation to be a great option for this -- it has the same sort of social structure and benefits as organized religion, but without requiring any particular sorts of beliefs or devotions. A lot of that has moved online these days -- I haven't tried this out but there are things like this https://www.sit-heads.com/

There are a lot of group sports (like run clubs or pickle ball) and art classes that are open sign ups where you don't need to know anyone to join, and you can just casually meet people. They might not become friends outside of the activity, but it's an easy entry point to feeling like you're part of your community. There used to be a lot of board game meet ups like this too, but the pandemic kind of killed the scene.

Sounds like you need a more drastic change to get you to snap out of your patterns. Maybe try moving to a new place? I suspect that if you move to a place that has been seeing a lot of population growth in the past couple of years (like Austin or Denver), it's probably easier to meet friends because there will be others in the same situation. You should also try to find an activity or hobby that you are into that has a social component to it. Or even something like volunteering or mentoring-- anything to get you out of the house and communicating more with people in the real world.

I had basically the same problem, and it doesn't help that I'm picky about the people whose company I enjoy, I found going to the mosque more helped me start developing an irl social circle again.

If you're not religious maybe something like a library or a hackspace could help? Going to hackspace helped alleviate some of my loneliness, even though I never managed to develop a social circle out of it.

There's quite a lot of online groups you can get involved in. My friend joined a DnD campaign on startplaying.games, for instance.

I am considering contacting the Employee assistance program for this. I have never used it and I am not sure if its a good idea.