If a carrier is a reputable company, they will make the changes that reflect throughout the system. Some carriers are really not carriers. They resell service from other real carriers. They are limited to being able to make CID changes to what they actually control, which is normally, not much.
So, as an example, a call is made and the routing selects "Jeb and Billy Bob's down home telephone shed" as a path for your call. They have no CID on their equipment, or if they do, it's relegated to something weird or not correct. The call ends up with missing or goofy CID.
The bottom line is if you want correct CID, you must keep meticulous records and hound your carrier to fix the problem. Armed with enough data and persistence, they will make the appropriate changes just to get you to stop bothering them.
Rcaman
