I hate to assume anything, but I am going to guess that you are looking for a remote site to route in a way in which you will be able to tell all the calls from that site are going through the PRI or gateway that is local to that site and providing them with local dial tone and Caller ID.
If that is the case and you only intend to do this without any additional configuration, then you will need to add an outside line code that is different from the others. For example: If you use 8.XXXXXXXXXX as your external pattern currently and you do not want to do any additional configuration, then on the Route Pattern Configuration page, the Gateway/Route List you select will need to be the PRI or trunk that the site is using. If the main site is using 8.XXXXXXXXXX, you could use 7.XXXXXXXXXX or 88.XXXXXXXXXX (You need to make sure whatever you choose is not already in use on your system as an extension range or other use) and that site would have to dial that to get out, otherwise they will be routed just like everyone else. Typically you would not configure it in this manner, you would use a CSS and/or a partition with a Route Group/Route List to accomplish this. I am not sure if the Local Route Groups were added by 9.5, but if they were, you would ideally use that method and then those calling from that site would appear to be calling locally.
Before I get into all the ways and steps necessary to configure this, could you post more information on what you are trying to accomplish exactly?
What we are trying to do is identify what area codes someone is calling from so they can routed between 2 different sales teams. For example if some calls from area code xxx they go to sales guy 1, but if they call from yyy they go to sales guy 2.