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.
All of them until I get voicemail.
With modern digital phones, the number of rings you hear when calling out doesn’t necessarily match the number of rings on the receiving end. The first few rings you hear when calling out are often “comfort noise” added locally by the network operator and are heard before the call is even fully routed to the receiver.