If I have one central office and 2 branch office. Central office process calls with call manager for central office and branches. Branches are using 1861 SRST routers. My question is can a person from central office call branch office's Local PSTN numbers? For example, if the Central office is in New York, and the branch office is in San Francisco, can a user in New York dial any local area number in San Francisco with out incurring long distance charge? If yes, how it can be implemented? What are the product and technology to do that?