It just occurred to me when calling my college roommate that basically, it’s three. With my mom, I let it go all the way to voicemail, as she’s nearly 80 and may be on the other end of the house.
But with most of my friends, if they don’t answer in two rings, it’s a lost cause absent external influences.
I try to always leave a voicemail so they know why I called. On my phone, voicemails are automatically transcribed, so I assume everyone has this.