Maybe I should add that I'm looking at ATM WAN switches and several-thousand-mile hauls. Are ATM WAN switches more sensitive? Can telcos clean up the noise on such a long haul as opposed to several-hundred-mile hauls. My counters on the routers for the 'short' haul lines are indeed zero.
If you can see errors, put on yor camo gear. Lines, international or otherwise, should run clean, whatever equipment is connected so long as it's correctly configured. Like 0 errors.
Well, do be careful. Most carries have "performance objectives" which they adhere to, and they specify some number of errored seconds per day per circuit, and those numbers may vary based on route-milage. Unfortunately I think most of those numbers are covered under NDAs, but I can safely say that 1 errored second/day would be well under the criteria and 1,000 would be well over, and anything in between depends on your carrier and route miles, etc., etc. --jhawk