I assume you have put the DID number in each extension setting for the caller ID to be displayed on outside calls. If your provider allows he names you use to be displayed, then it may be a mater of finding the correct combination of settings in the trunks outbound options. There are a number that deal with caller ID name and number, and where it is taken from, and how it is sent. You provider may be able to provide some information on what fields they make use of, helping to figure out what to change. Be sure to make note of the original settings as some changes may stop the trunk group from working completely. If you still have issues, post the name of your provider as others may have gone through the same thing and can offer suggestions as to the changes needed.