It's been at least 10 years since I've seen one in the wild, but never worked on one personally.

The 820/1236/2260 used to be very common around here though. One of our grocery chains had a 2260 in each store. Yes, a grocery store used that many CO lines believe it or not. When they replaced the 2260's they put in either NEC NEAX or Nortel Option 11.