Ohb - just read your thread in Chat. God he's a nasty fucker isn't he. Now I understand the tone of your posts on here.
Like most of the previous posters on your thread said, I'd offer him the contact centre, as per your offer of last May. So he thinks they're for crackheads? Actually, they're for violent, drunken, aggressive bullies like him, so he'd feel right at home.
No more phone calls, you don't need to listen to all his vile abuse. And I wouldn't believe his "I've changed" for a moment. If he has changed, let him make good on his promise to do whatever it takes. So contact centre first, and he can take it from there.
I see you've contacted your solicitor again, who you say is great. Hopefully she'll point you in the right direction. Everything is on your side. He walked away from contact. He pays no maintenance (I know the two aren't connected). He didn't take up your offer of a contact centre. He is known to the police. You have copies of abusive texts and emails.
Please don't speak to him. He's gaslighting you, you're still wondering if you imagined things. You didn't. Hopefully he'll get bored of not being able to swoop in to your ds's life and be Disney Dad from day one. He wants it all on his terms, well, that's not going to happen. He'll probably throw a strop, threaten to take you to court, tell your ds what a terrible mother you are, blah, blah, blah. But he won't. He sounds lazy, ignorant and the kind of man who won't fight through the courts.