I just got done pondering and then implementing this, so depending on what version of call manager you should be able to import/export to accomplish this. It took some time to get it tweaked so you better have a bunch of route filters to import to offset the time to make it work. In my case I had over 100 route filters to input. I was running CM version 6.1(2) at the time. The things you could import/export was limited with that version but route filters was one of them.

I manually created an example route filter with the max area codes, or in my case office codes that it would allow me to input. I saved it, then went to Bulk Administration -> Import/Export and exported the one route filter. Then downloaded my route filter that I was using as a template and used excel to create all the rest of route filters needed. Saved the new CSV and used 7-zip to tar up the CSV in order to create the header file and checksum the tar file containing the CSV's to make the input work.

It is my understanding that with CM version 7 you can import/export just about anything.

Hope that helps....