how do landline phones ring in France?

It is more like a prolonged ring lasting three seconds with a one second interval. Why don't you try for yourself by dialling say a tourist site after hours (6pm French time) when nobody will pick up and it won't cost you anything? For instance here is the number of the world famous Louvre Museum: 33 (0)1 40 20 50 50

Landlines all have different ringtones. Mine is a samba tune

I remember old telephones and they also had different ringing. Some had long ringings and some had short ones.

If you are asking what is the onomatopea of a phone ringing, it's "dring dring" or "drelin drelin"

Edit : When you are calling someone, the sound you can hear in the phone before the person answers is "biiiiiiiiiiiiiiiiiiiiiiiiiiiiiiip, biiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiip... " and after the person hangs up, it's "bip, bip, bip, bip..."