I usually just turn my phone off if I need to focus. If someone /really/ needs to reach me they could always call my workplace. And I avoid phone communication

I usually just turn my phone off if I need to focus. If someone /really/ needs to reach me they could always call my workplace. And I avoid phone communication at all cost anyway. I realise this is not an option for everyone of course. There's also apps that allow you to time lock your phone with exceptions for important things. Protip: set it up so you can get around it by rebooting the phone, in case you forgot to whitelist something, etc. Smartphones are painfully slow to boot anyway, so it still helps discourage the constant distraction if you can muster the will power to not do the reboot. More effort means you consider it rather than reflexively do it.